{ "type": "module", "source": "doc/api/buffer.md", "modules": [ { "textRaw": "Buffer", "name": "buffer", "introduced_in": "v0.1.90", "stability": 2, "stabilityText": "Stable", "desc": "
Source Code: lib/buffer.js
\nBuffer
objects are used to represent a fixed-length sequence of bytes. Many\nNode.js APIs support Buffer
s.
The Buffer
class is a subclass of JavaScript's Uint8Array
class and\nextends it with methods that cover additional use cases. Node.js APIs accept\nplain Uint8Array
s wherever Buffer
s are supported as well.
The Buffer
class is within the global scope, making it unlikely that one\nwould need to ever use require('buffer').Buffer
.
// Creates a zero-filled Buffer of length 10.\nconst buf1 = Buffer.alloc(10);\n\n// Creates a Buffer of length 10,\n// filled with bytes which all have the value `1`.\nconst buf2 = Buffer.alloc(10, 1);\n\n// Creates an uninitialized buffer of length 10.\n// This is faster than calling Buffer.alloc() but the returned\n// Buffer instance might contain old data that needs to be\n// overwritten using fill(), write(), or other functions that fill the Buffer's\n// contents.\nconst buf3 = Buffer.allocUnsafe(10);\n\n// Creates a Buffer containing the bytes [1, 2, 3].\nconst buf4 = Buffer.from([1, 2, 3]);\n\n// Creates a Buffer containing the bytes [1, 1, 1, 1] – the entries\n// are all truncated using `(value & 255)` to fit into the range 0–255.\nconst buf5 = Buffer.from([257, 257.5, -255, '1']);\n\n// Creates a Buffer containing the UTF-8-encoded bytes for the string 'tést':\n// [0x74, 0xc3, 0xa9, 0x73, 0x74] (in hexadecimal notation)\n// [116, 195, 169, 115, 116] (in decimal notation)\nconst buf6 = Buffer.from('tést');\n\n// Creates a Buffer containing the Latin-1 bytes [0x74, 0xe9, 0x73, 0x74].\nconst buf7 = Buffer.from('tést', 'latin1');\n
",
"modules": [
{
"textRaw": "Buffers and character encodings",
"name": "buffers_and_character_encodings",
"meta": {
"changes": [
{
"version": "v6.4.0",
"pr-url": "https://github.com/nodejs/node/pull/7111",
"description": "Introduced `latin1` as an alias for `binary`."
},
{
"version": "v5.0.0",
"pr-url": "https://github.com/nodejs/node/pull/2859",
"description": "Removed the deprecated `raw` and `raws` encodings."
}
]
},
"desc": "When converting between Buffer
s and strings, a character encoding may be\nspecified. If no character encoding is specified, UTF-8 will be used as the\ndefault.
const buf = Buffer.from('hello world', 'utf8');\n\nconsole.log(buf.toString('hex'));\n// Prints: 68656c6c6f20776f726c64\nconsole.log(buf.toString('base64'));\n// Prints: aGVsbG8gd29ybGQ=\n\nconsole.log(Buffer.from('fhqwhgads', 'utf8'));\n// Prints: <Buffer 66 68 71 77 68 67 61 64 73>\nconsole.log(Buffer.from('fhqwhgads', 'utf16le'));\n// Prints: <Buffer 66 00 68 00 71 00 77 00 68 00 67 00 61 00 64 00 73 00>\n
\nThe character encodings currently supported by Node.js are the following:
\n'utf8'
: Multi-byte encoded Unicode characters. Many web pages and other\ndocument formats use UTF-8. This is the default character encoding.\nWhen decoding a Buffer
into a string that does not exclusively contain\nvalid UTF-8 data, the Unicode replacement character U+FFFD
� will be used\nto represent those errors.
'utf16le'
: Multi-byte encoded Unicode characters. Unlike 'utf8'
, each\ncharacter in the string will be encoded using either 2 or 4 bytes.\nNode.js only supports the little-endian variant of UTF-16.
'latin1'
: Latin-1 stands for ISO-8859-1. This character encoding only\nsupports the Unicode characters from U+0000
to U+00FF
. Each character is\nencoded using a single byte. Characters that do not fit into that range are\ntruncated and will be mapped to characters in that range.
Converting a Buffer
into a string using one of the above is referred to as\ndecoding, and converting a string into a Buffer
is referred to as encoding.
Node.js also supports the following two binary-to-text encodings. For\nbinary-to-text encodings, the naming convention is reversed: Converting a\nBuffer
into a string is typically referred to as encoding, and converting a\nstring into a Buffer
as decoding.
'base64'
: Base64 encoding. When creating a Buffer
from a string,\nthis encoding will also correctly accept \"URL and Filename Safe Alphabet\" as\nspecified in RFC 4648, Section 5. Whitespace characters such as spaces,\ntabs, and new lines contained within the base64-encoded string are ignored.
'hex'
: Encode each byte as two hexadecimal characters. Data truncation\nmay occur when decoding string that do exclusively contain valid hexadecimal\ncharacters. See below for an example.
The following legacy character encodings are also supported:
\n'ascii'
: For 7-bit ASCII data only. When encoding a string into a\nBuffer
, this is equivalent to using 'latin1'
. When decoding a Buffer
\ninto a string, using encoding this will additionally unset the highest bit of\neach byte before decoding as 'latin1'
.\nGenerally, there should be no reason to use this encoding, as 'utf8'
\n(or, if the data is known to always be ASCII-only, 'latin1'
) will be a\nbetter choice when encoding or decoding ASCII-only text. It is only provided\nfor legacy compatibility.
'binary'
: Alias for 'latin1'
. See binary strings for more background\non this topic. The name of this encoding can be very misleading, as all of the\nencodings listed here convert between strings and binary data. For converting\nbetween strings and Buffer
s, typically 'utf-8'
is the right choice.
'ucs2'
: Alias of 'utf16le'
. UCS-2 used to refer to a variant of UTF-16\nthat did not support characters that had code points larger than U+FFFF.\nIn Node.js, these code points are always supported.
Buffer.from('1ag', 'hex');\n// Prints <Buffer 1a>, data truncated when first non-hexadecimal value\n// ('g') encountered.\n\nBuffer.from('1a7g', 'hex');\n// Prints <Buffer 1a>, data truncated when data ends in single digit ('7').\n\nBuffer.from('1634', 'hex');\n// Prints <Buffer 16 34>, all data represented.\n
\nModern Web browsers follow the WHATWG Encoding Standard which aliases\nboth 'latin1'
and 'ISO-8859-1'
to 'win-1252'
. This means that while doing\nsomething like http.get()
, if the returned charset is one of those listed in\nthe WHATWG specification it is possible that the server actually returned\n'win-1252'
-encoded data, and using 'latin1'
encoding may incorrectly decode\nthe characters.
Buffer
instances are also JavaScript Uint8Array
and TypedArray
\ninstances. All TypedArray
methods are available on Buffer
s. There are,\nhowever, subtle incompatibilities between the Buffer
API and the\nTypedArray
API.
In particular:
\nTypedArray#slice()
creates a copy of part of the TypedArray
,\nBuffer#slice()
creates a view over the existing Buffer
\nwithout copying. This behavior can be surprising, and only exists for legacy\ncompatibility. TypedArray#subarray()
can be used to achieve the behavior\nof Buffer#slice()
on both Buffer
s and other\nTypedArray
s.buf.toString()
is incompatible with its TypedArray
equivalent.buf.indexOf()
, support additional arguments.There are two ways to create new TypedArray
instances from a Buffer
:
Buffer
to a TypedArray
constructor will copy the Buffer
s\ncontents, interpreted an array array of integers, and not as a byte sequence\nof the target type.const buf = Buffer.from([1, 2, 3, 4]);\nconst uint32array = new Uint32Array(buf);\n\nconsole.log(uint32array);\n\n// Prints: Uint32Array(4) [ 1, 2, 3, 4 ]\n
\nBuffer
s underlying ArrayBuffer
will create a\nTypedArray
that shares its memory with the Buffer
.const buf = Buffer.from('hello', 'utf16le');\nconst uint16arr = new Uint16Array(\n buf.buffer,\n buf.byteOffset,\n buf.length / Uint16Array.BYTES_PER_ELEMENT);\n\nconsole.log(uint16array);\n\n// Prints: Uint16Array(5) [ 104, 101, 108, 108, 111 ]\n
\nIt is possible to create a new Buffer
that shares the same allocated\nmemory as a TypedArray
instance by using the TypedArray
object’s\n.buffer
property in the same way. Buffer.from()
\nbehaves like new Uint8Array()
in this context.
const arr = new Uint16Array(2);\n\narr[0] = 5000;\narr[1] = 4000;\n\n// Copies the contents of `arr`.\nconst buf1 = Buffer.from(arr);\n\n// Shares memory with `arr`.\nconst buf2 = Buffer.from(arr.buffer);\n\nconsole.log(buf1);\n// Prints: <Buffer 88 a0>\nconsole.log(buf2);\n// Prints: <Buffer 88 13 a0 0f>\n\narr[1] = 6000;\n\nconsole.log(buf1);\n// Prints: <Buffer 88 a0>\nconsole.log(buf2);\n// Prints: <Buffer 88 13 70 17>\n
\nWhen creating a Buffer
using a TypedArray
's .buffer
, it is\npossible to use only a portion of the underlying ArrayBuffer
by passing in\nbyteOffset
and length
parameters.
const arr = new Uint16Array(20);\nconst buf = Buffer.from(arr.buffer, 0, 16);\n\nconsole.log(buf.length);\n// Prints: 16\n
\nThe Buffer.from()
and TypedArray.from()
have different signatures and\nimplementations. Specifically, the TypedArray
variants accept a second\nargument that is a mapping function that is invoked on every element of the\ntyped array:
TypedArray.from(source[, mapFn[, thisArg]])
The Buffer.from()
method, however, does not support the use of a mapping\nfunction:
Buffer.from(array)
Buffer.from(buffer)
Buffer.from(arrayBuffer[, byteOffset[, length]])
Buffer.from(string[, encoding])
Buffer
instances can be iterated over using for..of
syntax:
const buf = Buffer.from([1, 2, 3]);\n\nfor (const b of buf) {\n console.log(b);\n}\n// Prints:\n// 1\n// 2\n// 3\n
\nAdditionally, the buf.values()
, buf.keys()
, and\nbuf.entries()
methods can be used to create iterators.
While, the Buffer
object is available as a global, there are additional\nBuffer
-related APIs that are available only via the buffer
module\naccessed using require('buffer')
.
Returns the maximum number of bytes that will be returned when\nbuf.inspect()
is called. This can be overridden by user modules. See\nutil.inspect()
for more details on buf.inspect()
behavior.
An alias for buffer.constants.MAX_LENGTH
.
Re-encodes the given Buffer
or Uint8Array
instance from one character\nencoding to another. Returns a new Buffer
instance.
Throws if the fromEnc
or toEnc
specify invalid character encodings or if\nconversion from fromEnc
to toEnc
is not permitted.
Encodings supported by buffer.transcode()
are: 'ascii'
, 'utf8'
,\n'utf16le'
, 'ucs2'
, 'latin1'
, and 'binary'
.
The transcoding process will use substitution characters if a given byte\nsequence cannot be adequately represented in the target encoding. For instance:
\nconst buffer = require('buffer');\n\nconst newBuf = buffer.transcode(Buffer.from('€'), 'utf8', 'ascii');\nconsole.log(newBuf.toString('ascii'));\n// Prints: '?'\n
\nBecause the Euro (€
) sign is not representable in US-ASCII, it is replaced\nwith ?
in the transcoded Buffer
.
See Buffer.allocUnsafeSlow()
. This was never a class in the sense that\nthe constructor always returned a Buffer
instance, rather than a SlowBuffer
\ninstance.
On 32-bit architectures, this value currently is (2^30)-1
(~1GB).\nOn 64-bit architectures, this value currently is (2^31)-1
(~2GB).
This value is also available as buffer.kMaxLength
.
Represents the largest length
that a string
primitive can have, counted\nin UTF-16 code units.
This value may depend on the JS engine that is being used.
", "shortDesc": "The largest length allowed for a single `string` instance." } ], "type": "module", "displayName": "Buffer constants" } ], "type": "module", "displayName": "`buffer` module APIs" }, { "textRaw": "`Buffer.from()`, `Buffer.alloc()`, and `Buffer.allocUnsafe()`", "name": "`buffer.from()`,_`buffer.alloc()`,_and_`buffer.allocunsafe()`", "desc": "In versions of Node.js prior to 6.0.0, Buffer
instances were created using the\nBuffer
constructor function, which allocates the returned Buffer
\ndifferently based on what arguments are provided:
Buffer()
(e.g. new Buffer(10)
)\nallocates a new Buffer
object of the specified size. Prior to Node.js 8.0.0,\nthe memory allocated for such Buffer
instances is not initialized and\ncan contain sensitive data. Such Buffer
instances must be subsequently\ninitialized by using either buf.fill(0)
or by writing to the\nentire Buffer
before reading data from the Buffer
.\nWhile this behavior is intentional to improve performance,\ndevelopment experience has demonstrated that a more explicit distinction is\nrequired between creating a fast-but-uninitialized Buffer
versus creating a\nslower-but-safer Buffer
. Since Node.js 8.0.0, Buffer(num)
and new Buffer(num)
return a Buffer
with initialized memory.Buffer
as the first argument copies the\npassed object's data into the Buffer
.ArrayBuffer
or a SharedArrayBuffer
returns a Buffer
\nthat shares allocated memory with the given array buffer.Because the behavior of new Buffer()
is different depending on the type of the\nfirst argument, security and reliability issues can be inadvertently introduced\ninto applications when argument validation or Buffer
initialization is not\nperformed.
For example, if an attacker can cause an application to receive a number where\na string is expected, the application may call new Buffer(100)
\ninstead of new Buffer(\"100\")
, leading it to allocate a 100 byte buffer instead\nof allocating a 3 byte buffer with content \"100\"
. This is commonly possible\nusing JSON API calls. Since JSON distinguishes between numeric and string types,\nit allows injection of numbers where a naively written application that does not\nvalidate its input sufficiently might expect to always receive a string.\nBefore Node.js 8.0.0, the 100 byte buffer might contain\narbitrary pre-existing in-memory data, so may be used to expose in-memory\nsecrets to a remote attacker. Since Node.js 8.0.0, exposure of memory cannot\noccur because the data is zero-filled. However, other attacks are still\npossible, such as causing very large buffers to be allocated by the server,\nleading to performance degradation or crashing on memory exhaustion.
To make the creation of Buffer
instances more reliable and less error-prone,\nthe various forms of the new Buffer()
constructor have been deprecated\nand replaced by separate Buffer.from()
, Buffer.alloc()
, and\nBuffer.allocUnsafe()
methods.
Developers should migrate all existing uses of the new Buffer()
constructors\nto one of these new APIs.
Buffer.from(array)
returns a new Buffer
that contains a copy of the\nprovided octets.Buffer.from(arrayBuffer[, byteOffset[, length]])
\nreturns a new Buffer
that shares the same allocated memory as the given\nArrayBuffer
.Buffer.from(buffer)
returns a new Buffer
that contains a copy of the\ncontents of the given Buffer
.Buffer.from(string[, encoding])
returns a new\nBuffer
that contains a copy of the provided string.Buffer.alloc(size[, fill[, encoding]])
returns a new\ninitialized Buffer
of the specified size. This method is slower than\nBuffer.allocUnsafe(size)
but guarantees that newly\ncreated Buffer
instances never contain old data that is potentially\nsensitive. A TypeError
will be thrown if size
is not a number.Buffer.allocUnsafe(size)
and\nBuffer.allocUnsafeSlow(size)
each return a\nnew uninitialized Buffer
of the specified size
. Because the Buffer
is\nuninitialized, the allocated segment of memory might contain old data that is\npotentially sensitive.Buffer
instances returned by Buffer.allocUnsafe()
and\nBuffer.from(array)
may be allocated off a shared internal memory pool\nif size
is less than or equal to half Buffer.poolSize
. Instances\nreturned by Buffer.allocUnsafeSlow()
never use the shared internal\nmemory pool.
Node.js can be started using the --zero-fill-buffers
command line option to\ncause all newly-allocated Buffer
instances to be zero-filled upon creation by\ndefault. Without the option, buffers created with Buffer.allocUnsafe()
,\nBuffer.allocUnsafeSlow()
, and new SlowBuffer(size)
are not zero-filled.\nUse of this flag can have a measurable negative impact on performance. Use the\n--zero-fill-buffers
option only when necessary to enforce that newly allocated\nBuffer
instances cannot contain old data that is potentially sensitive.
$ node --zero-fill-buffers\n> Buffer.allocUnsafe(5);\n<Buffer 00 00 00 00 00>\n
",
"type": "module",
"displayName": "The `--zero-fill-buffers` command line option"
},
{
"textRaw": "What makes `Buffer.allocUnsafe()` and `Buffer.allocUnsafeSlow()` \"unsafe\"?",
"name": "what_makes_`buffer.allocunsafe()`_and_`buffer.allocunsafeslow()`_\"unsafe\"?",
"desc": "When calling Buffer.allocUnsafe()
and Buffer.allocUnsafeSlow()
, the\nsegment of allocated memory is uninitialized (it is not zeroed-out). While\nthis design makes the allocation of memory quite fast, the allocated segment of\nmemory might contain old data that is potentially sensitive. Using a Buffer
\ncreated by Buffer.allocUnsafe()
without completely overwriting the\nmemory can allow this old data to be leaked when the Buffer
memory is read.
While there are clear performance advantages to using\nBuffer.allocUnsafe()
, extra care must be taken in order to avoid\nintroducing security vulnerabilities into an application.
The Buffer
class is a global type for dealing with binary data directly.\nIt can be constructed in a variety of ways.
Allocates a new Buffer
of size
bytes. If fill
is undefined
, the\nBuffer
will be zero-filled.
const buf = Buffer.alloc(5);\n\nconsole.log(buf);\n// Prints: <Buffer 00 00 00 00 00>\n
\nIf size
is larger than\nbuffer.constants.MAX_LENGTH
or smaller than 0, ERR_INVALID_OPT_VALUE
\nis thrown.
If fill
is specified, the allocated Buffer
will be initialized by calling\nbuf.fill(fill)
.
const buf = Buffer.alloc(5, 'a');\n\nconsole.log(buf);\n// Prints: <Buffer 61 61 61 61 61>\n
\nIf both fill
and encoding
are specified, the allocated Buffer
will be\ninitialized by calling buf.fill(fill, encoding)
.
const buf = Buffer.alloc(11, 'aGVsbG8gd29ybGQ=', 'base64');\n\nconsole.log(buf);\n// Prints: <Buffer 68 65 6c 6c 6f 20 77 6f 72 6c 64>\n
\nCalling Buffer.alloc()
can be measurably slower than the alternative\nBuffer.allocUnsafe()
but ensures that the newly created Buffer
instance\ncontents will never contain sensitive data from previous allocations, including\ndata that might not have been allocated for Buffer
s.
A TypeError
will be thrown if size
is not a number.
Allocates a new Buffer
of size
bytes. If size
is larger than\nbuffer.constants.MAX_LENGTH
or smaller than 0, ERR_INVALID_OPT_VALUE
\nis thrown.
The underlying memory for Buffer
instances created in this way is not\ninitialized. The contents of the newly created Buffer
are unknown and\nmay contain sensitive data. Use Buffer.alloc()
instead to initialize\nBuffer
instances with zeroes.
const buf = Buffer.allocUnsafe(10);\n\nconsole.log(buf);\n// Prints (contents may vary): <Buffer a0 8b 28 3f 01 00 00 00 50 32>\n\nbuf.fill(0);\n\nconsole.log(buf);\n// Prints: <Buffer 00 00 00 00 00 00 00 00 00 00>\n
\nA TypeError
will be thrown if size
is not a number.
The Buffer
module pre-allocates an internal Buffer
instance of\nsize Buffer.poolSize
that is used as a pool for the fast allocation of new\nBuffer
instances created using Buffer.allocUnsafe()
,\nBuffer.from(array)
, and the deprecated new Buffer(size)
constructor only\nwhen size
is less than or equal to Buffer.poolSize >> 1
(floor of\nBuffer.poolSize
divided by two).
Use of this pre-allocated internal memory pool is a key difference between\ncalling Buffer.alloc(size, fill)
vs. Buffer.allocUnsafe(size).fill(fill)
.\nSpecifically, Buffer.alloc(size, fill)
will never use the internal Buffer
\npool, while Buffer.allocUnsafe(size).fill(fill)
will use the internal\nBuffer
pool if size
is less than or equal to half Buffer.poolSize
. The\ndifference is subtle but can be important when an application requires the\nadditional performance that Buffer.allocUnsafe()
provides.
Allocates a new Buffer
of size
bytes. If size
is larger than\nbuffer.constants.MAX_LENGTH
or smaller than 0, ERR_INVALID_OPT_VALUE
\nis thrown. A zero-length Buffer
is created if size
is 0.
The underlying memory for Buffer
instances created in this way is not\ninitialized. The contents of the newly created Buffer
are unknown and\nmay contain sensitive data. Use buf.fill(0)
to initialize\nsuch Buffer
instances with zeroes.
When using Buffer.allocUnsafe()
to allocate new Buffer
instances,\nallocations under 4KB are sliced from a single pre-allocated Buffer
. This\nallows applications to avoid the garbage collection overhead of creating many\nindividually allocated Buffer
instances. This approach improves both\nperformance and memory usage by eliminating the need to track and clean up as\nmany individual ArrayBuffer
objects.
However, in the case where a developer may need to retain a small chunk of\nmemory from a pool for an indeterminate amount of time, it may be appropriate\nto create an un-pooled Buffer
instance using Buffer.allocUnsafeSlow()
and\nthen copying out the relevant bits.
// Need to keep around a few small chunks of memory.\nconst store = [];\n\nsocket.on('readable', () => {\n let data;\n while (null !== (data = readable.read())) {\n // Allocate for retained data.\n const sb = Buffer.allocUnsafeSlow(10);\n\n // Copy the data into the new allocation.\n data.copy(sb, 0, 0, 10);\n\n store.push(sb);\n }\n});\n
\nA TypeError
will be thrown if size
is not a number.
Returns the byte length of a string when encoded using encoding
.\nThis is not the same as String.prototype.length
, which does not account\nfor the encoding that is used to convert the string into bytes.
For 'base64'
and 'hex'
, this function assumes valid input. For strings that\ncontain non-base64/hex-encoded data (e.g. whitespace), the return value might be\ngreater than the length of a Buffer
created from the string.
const str = '\\u00bd + \\u00bc = \\u00be';\n\nconsole.log(`${str}: ${str.length} characters, ` +\n `${Buffer.byteLength(str, 'utf8')} bytes`);\n// Prints: ½ + ¼ = ¾: 9 characters, 12 bytes\n
\nWhen string
is a Buffer
/DataView
/TypedArray
/ArrayBuffer
/\nSharedArrayBuffer
, the byte length as reported by .byteLength
\nis returned.
Compares buf1
to buf2
, typically for the purpose of sorting arrays of\nBuffer
instances. This is equivalent to calling\nbuf1.compare(buf2)
.
const buf1 = Buffer.from('1234');\nconst buf2 = Buffer.from('0123');\nconst arr = [buf1, buf2];\n\nconsole.log(arr.sort(Buffer.compare));\n// Prints: [ <Buffer 30 31 32 33>, <Buffer 31 32 33 34> ]\n// (This result is equal to: [buf2, buf1].)\n
"
},
{
"textRaw": "Class Method: `Buffer.concat(list[, totalLength])`",
"type": "classMethod",
"name": "concat",
"meta": {
"added": [
"v0.7.11"
],
"changes": [
{
"version": "v8.0.0",
"pr-url": "https://github.com/nodejs/node/pull/10236",
"description": "The elements of `list` can now be `Uint8Array`s."
}
]
},
"signatures": [
{
"return": {
"textRaw": "Returns: {Buffer}",
"name": "return",
"type": "Buffer"
},
"params": [
{
"textRaw": "`list` {Buffer[] | Uint8Array[]} List of `Buffer` or [`Uint8Array`][] instances to concatenate.",
"name": "list",
"type": "Buffer[] | Uint8Array[]",
"desc": "List of `Buffer` or [`Uint8Array`][] instances to concatenate."
},
{
"textRaw": "`totalLength` {integer} Total length of the `Buffer` instances in `list` when concatenated.",
"name": "totalLength",
"type": "integer",
"desc": "Total length of the `Buffer` instances in `list` when concatenated."
}
]
}
],
"desc": "Returns a new Buffer
which is the result of concatenating all the Buffer
\ninstances in the list
together.
If the list has no items, or if the totalLength
is 0, then a new zero-length\nBuffer
is returned.
If totalLength
is not provided, it is calculated from the Buffer
instances\nin list
by adding their lengths.
If totalLength
is provided, it is coerced to an unsigned integer. If the\ncombined length of the Buffer
s in list
exceeds totalLength
, the result is\ntruncated to totalLength
.
// Create a single `Buffer` from a list of three `Buffer` instances.\n\nconst buf1 = Buffer.alloc(10);\nconst buf2 = Buffer.alloc(14);\nconst buf3 = Buffer.alloc(18);\nconst totalLength = buf1.length + buf2.length + buf3.length;\n\nconsole.log(totalLength);\n// Prints: 42\n\nconst bufA = Buffer.concat([buf1, buf2, buf3], totalLength);\n\nconsole.log(bufA);\n// Prints: <Buffer 00 00 00 00 ...>\nconsole.log(bufA.length);\n// Prints: 42\n
"
},
{
"textRaw": "Class Method: `Buffer.from(array)`",
"type": "classMethod",
"name": "from",
"meta": {
"added": [
"v5.10.0"
],
"changes": []
},
"signatures": [
{
"params": [
{
"textRaw": "`array` {integer[]}",
"name": "array",
"type": "integer[]"
}
]
}
],
"desc": "Allocates a new Buffer
using an array
of bytes in the range 0
– 255
.\nArray entries outside that range will be truncated to fit into it.
// Creates a new Buffer containing the UTF-8 bytes of the string 'buffer'.\nconst buf = Buffer.from([0x62, 0x75, 0x66, 0x66, 0x65, 0x72]);\n
\nA TypeError
will be thrown if array
is not an Array
or another type\nappropriate for Buffer.from()
variants.
Buffer.from(array)
and Buffer.from(string)
may also use the internal\nBuffer
pool like Buffer.allocUnsafe()
does.
This creates a view of the ArrayBuffer
without copying the underlying\nmemory. For example, when passed a reference to the .buffer
property of a\nTypedArray
instance, the newly created Buffer
will share the same\nallocated memory as the TypedArray
.
const arr = new Uint16Array(2);\n\narr[0] = 5000;\narr[1] = 4000;\n\n// Shares memory with `arr`.\nconst buf = Buffer.from(arr.buffer);\n\nconsole.log(buf);\n// Prints: <Buffer 88 13 a0 0f>\n\n// Changing the original Uint16Array changes the Buffer also.\narr[1] = 6000;\n\nconsole.log(buf);\n// Prints: <Buffer 88 13 70 17>\n
\nThe optional byteOffset
and length
arguments specify a memory range within\nthe arrayBuffer
that will be shared by the Buffer
.
const ab = new ArrayBuffer(10);\nconst buf = Buffer.from(ab, 0, 2);\n\nconsole.log(buf.length);\n// Prints: 2\n
\nA TypeError
will be thrown if arrayBuffer
is not an ArrayBuffer
or a\nSharedArrayBuffer
or another type appropriate for Buffer.from()
\nvariants.
Copies the passed buffer
data onto a new Buffer
instance.
const buf1 = Buffer.from('buffer');\nconst buf2 = Buffer.from(buf1);\n\nbuf1[0] = 0x61;\n\nconsole.log(buf1.toString());\n// Prints: auffer\nconsole.log(buf2.toString());\n// Prints: buffer\n
\nA TypeError
will be thrown if buffer
is not a Buffer
or another type\nappropriate for Buffer.from()
variants.
For objects whose valueOf()
function returns a value not strictly equal to\nobject
, returns Buffer.from(object.valueOf(), offsetOrEncoding, length)
.
const buf = Buffer.from(new String('this is a test'));\n// Prints: <Buffer 74 68 69 73 20 69 73 20 61 20 74 65 73 74>\n
\nFor objects that support Symbol.toPrimitive
, returns\nBuffer.from(object[Symbol.toPrimitive]('string'), offsetOrEncoding)
.
class Foo {\n [Symbol.toPrimitive]() {\n return 'this is a test';\n }\n}\n\nconst buf = Buffer.from(new Foo(), 'utf8');\n// Prints: <Buffer 74 68 69 73 20 69 73 20 61 20 74 65 73 74>\n
\nA TypeError
will be thrown if object
does not have the mentioned methods or\nis not of another type appropriate for Buffer.from()
variants.
Creates a new Buffer
containing string
. The encoding
parameter identifies\nthe character encoding to be used when converting string
into bytes.
const buf1 = Buffer.from('this is a tést');\nconst buf2 = Buffer.from('7468697320697320612074c3a97374', 'hex');\n\nconsole.log(buf1.toString());\n// Prints: this is a tést\nconsole.log(buf2.toString());\n// Prints: this is a tést\nconsole.log(buf1.toString('latin1'));\n// Prints: this is a tést\n
\nA TypeError
will be thrown if string
is not a string or another type\nappropriate for Buffer.from()
variants.
Returns true
if obj
is a Buffer
, false
otherwise.
Returns true
if encoding
is the name of a supported character encoding,\nor false
otherwise.
console.log(Buffer.isEncoding('utf-8'));\n// Prints: true\n\nconsole.log(Buffer.isEncoding('hex'));\n// Prints: true\n\nconsole.log(Buffer.isEncoding('utf/8'));\n// Prints: false\n\nconsole.log(Buffer.isEncoding(''));\n// Prints: false\n
"
}
],
"properties": [
{
"textRaw": "`poolSize` {integer} **Default:** `8192`",
"type": "integer",
"name": "poolSize",
"meta": {
"added": [
"v0.11.3"
],
"changes": []
},
"default": "`8192`",
"desc": "This is the size (in bytes) of pre-allocated internal Buffer
instances used\nfor pooling. This value may be modified.
The index operator [index]
can be used to get and set the octet at position\nindex
in buf
. The values refer to individual bytes, so the legal value\nrange is between 0x00
and 0xFF
(hex) or 0
and 255
(decimal).
This operator is inherited from Uint8Array
, so its behavior on out-of-bounds\naccess is the same as Uint8Array
. In other words, buf[index]
returns\nundefined
when index
is negative or greater or equal to buf.length
, and\nbuf[index] = value
does not modify the buffer if index
is negative or\n>= buf.length
.
// Copy an ASCII string into a `Buffer` one byte at a time.\n// (This only works for ASCII-only strings. In general, one should use\n// `Buffer.from()` to perform this conversion.)\n\nconst str = 'Node.js';\nconst buf = Buffer.allocUnsafe(str.length);\n\nfor (let i = 0; i < str.length; i++) {\n buf[i] = str.charCodeAt(i);\n}\n\nconsole.log(buf.toString('utf8'));\n// Prints: Node.js\n
"
},
{
"textRaw": "`buffer` {ArrayBuffer} The underlying `ArrayBuffer` object based on which this `Buffer` object is created.",
"type": "ArrayBuffer",
"name": "buffer",
"desc": "This ArrayBuffer
is not guaranteed to correspond exactly to the original\nBuffer
. See the notes on buf.byteOffset
for details.
const arrayBuffer = new ArrayBuffer(16);\nconst buffer = Buffer.from(arrayBuffer);\n\nconsole.log(buffer.buffer === arrayBuffer);\n// Prints: true\n
",
"shortDesc": "The underlying `ArrayBuffer` object based on which this `Buffer` object is created."
},
{
"textRaw": "`byteOffset` {integer} The `byteOffset` of the `Buffer`s underlying `ArrayBuffer` object.",
"type": "integer",
"name": "byteOffset",
"desc": "When setting byteOffset
in Buffer.from(ArrayBuffer, byteOffset, length)
,\nor sometimes when allocating a Buffer
smaller than Buffer.poolSize
, the\nbuffer does not start from a zero offset on the underlying ArrayBuffer
.
This can cause problems when accessing the underlying ArrayBuffer
directly\nusing buf.buffer
, as other parts of the ArrayBuffer
may be unrelated\nto the Buffer
object itself.
A common issue when creating a TypedArray
object that shares its memory with\na Buffer
is that in this case one needs to specify the byteOffset
correctly:
// Create a buffer smaller than `Buffer.poolSize`.\nconst nodeBuffer = new Buffer.from([0, 1, 2, 3, 4, 5, 6, 7, 8, 9]);\n\n// When casting the Node.js Buffer to an Int8Array, use the byteOffset\n// to refer only to the part of `nodeBuffer.buffer` that contains the memory\n// for `nodeBuffer`.\nnew Int8Array(nodeBuffer.buffer, nodeBuffer.byteOffset, nodeBuffer.length);\n
",
"shortDesc": "The `byteOffset` of the `Buffer`s underlying `ArrayBuffer` object."
},
{
"textRaw": "`length` {integer}",
"type": "integer",
"name": "length",
"meta": {
"added": [
"v0.1.90"
],
"changes": []
},
"desc": "Returns the number of bytes in buf
.
// Create a `Buffer` and write a shorter string to it using UTF-8.\n\nconst buf = Buffer.alloc(1234);\n\nconsole.log(buf.length);\n// Prints: 1234\n\nbuf.write('some string', 0, 'utf8');\n\nconsole.log(buf.length);\n// Prints: 1234\n
"
},
{
"textRaw": "`buf.parent`",
"name": "parent",
"meta": {
"deprecated": [
"v8.0.0"
],
"changes": []
},
"stability": 0,
"stabilityText": "Deprecated: Use [`buf.buffer`][] instead.",
"desc": "The buf.parent
property is a deprecated alias for buf.buffer
.
Compares buf
with target
and returns a number indicating whether buf
\ncomes before, after, or is the same as target
in sort order.\nComparison is based on the actual sequence of bytes in each Buffer
.
0
is returned if target
is the same as buf
1
is returned if target
should come before buf
when sorted.-1
is returned if target
should come after buf
when sorted.const buf1 = Buffer.from('ABC');\nconst buf2 = Buffer.from('BCD');\nconst buf3 = Buffer.from('ABCD');\n\nconsole.log(buf1.compare(buf1));\n// Prints: 0\nconsole.log(buf1.compare(buf2));\n// Prints: -1\nconsole.log(buf1.compare(buf3));\n// Prints: -1\nconsole.log(buf2.compare(buf1));\n// Prints: 1\nconsole.log(buf2.compare(buf3));\n// Prints: 1\nconsole.log([buf1, buf2, buf3].sort(Buffer.compare));\n// Prints: [ <Buffer 41 42 43>, <Buffer 41 42 43 44>, <Buffer 42 43 44> ]\n// (This result is equal to: [buf1, buf3, buf2].)\n
\nThe optional targetStart
, targetEnd
, sourceStart
, and sourceEnd
\narguments can be used to limit the comparison to specific ranges within target
\nand buf
respectively.
const buf1 = Buffer.from([1, 2, 3, 4, 5, 6, 7, 8, 9]);\nconst buf2 = Buffer.from([5, 6, 7, 8, 9, 1, 2, 3, 4]);\n\nconsole.log(buf1.compare(buf2, 5, 9, 0, 4));\n// Prints: 0\nconsole.log(buf1.compare(buf2, 0, 6, 4));\n// Prints: -1\nconsole.log(buf1.compare(buf2, 5, 6, 5));\n// Prints: 1\n
\nERR_OUT_OF_RANGE
is thrown if targetStart < 0
, sourceStart < 0
,\ntargetEnd > target.byteLength
, or sourceEnd > source.byteLength
.
Copies data from a region of buf
to a region in target
, even if the target
\nmemory region overlaps with buf
.
TypedArray#set()
performs the same operation, and is available for all\nTypedArrays, including Node.js Buffer
s, although it takes different\nfunction arguments.
// Create two `Buffer` instances.\nconst buf1 = Buffer.allocUnsafe(26);\nconst buf2 = Buffer.allocUnsafe(26).fill('!');\n\nfor (let i = 0; i < 26; i++) {\n // 97 is the decimal ASCII value for 'a'.\n buf1[i] = i + 97;\n}\n\n// Copy `buf1` bytes 16 through 19 into `buf2` starting at byte 8 of `buf2`.\nbuf1.copy(buf2, 8, 16, 20);\n// This is equivalent to:\n// buf2.set(buf1.subarray(16, 20), 8);\n\nconsole.log(buf2.toString('ascii', 0, 25));\n// Prints: !!!!!!!!qrst!!!!!!!!!!!!!\n
\n// Create a `Buffer` and copy data from one region to an overlapping region\n// within the same `Buffer`.\n\nconst buf = Buffer.allocUnsafe(26);\n\nfor (let i = 0; i < 26; i++) {\n // 97 is the decimal ASCII value for 'a'.\n buf[i] = i + 97;\n}\n\nbuf.copy(buf, 0, 4, 10);\n\nconsole.log(buf.toString());\n// Prints: efghijghijklmnopqrstuvwxyz\n
"
},
{
"textRaw": "`buf.entries()`",
"type": "method",
"name": "entries",
"meta": {
"added": [
"v1.1.0"
],
"changes": []
},
"signatures": [
{
"return": {
"textRaw": "Returns: {Iterator}",
"name": "return",
"type": "Iterator"
},
"params": []
}
],
"desc": "Creates and returns an iterator of [index, byte]
pairs from the contents\nof buf
.
// Log the entire contents of a `Buffer`.\n\nconst buf = Buffer.from('buffer');\n\nfor (const pair of buf.entries()) {\n console.log(pair);\n}\n// Prints:\n// [0, 98]\n// [1, 117]\n// [2, 102]\n// [3, 102]\n// [4, 101]\n// [5, 114]\n
"
},
{
"textRaw": "`buf.equals(otherBuffer)`",
"type": "method",
"name": "equals",
"meta": {
"added": [
"v0.11.13"
],
"changes": [
{
"version": "v8.0.0",
"pr-url": "https://github.com/nodejs/node/pull/10236",
"description": "The arguments can now be `Uint8Array`s."
}
]
},
"signatures": [
{
"return": {
"textRaw": "Returns: {boolean}",
"name": "return",
"type": "boolean"
},
"params": [
{
"textRaw": "`otherBuffer` {Buffer|Uint8Array} A `Buffer` or [`Uint8Array`][] with which to compare `buf`.",
"name": "otherBuffer",
"type": "Buffer|Uint8Array",
"desc": "A `Buffer` or [`Uint8Array`][] with which to compare `buf`."
}
]
}
],
"desc": "Returns true
if both buf
and otherBuffer
have exactly the same bytes,\nfalse
otherwise. Equivalent to\nbuf.compare(otherBuffer) === 0
.
const buf1 = Buffer.from('ABC');\nconst buf2 = Buffer.from('414243', 'hex');\nconst buf3 = Buffer.from('ABCD');\n\nconsole.log(buf1.equals(buf2));\n// Prints: true\nconsole.log(buf1.equals(buf3));\n// Prints: false\n
"
},
{
"textRaw": "`buf.fill(value[, offset[, end]][, encoding])`",
"type": "method",
"name": "fill",
"meta": {
"added": [
"v0.5.0"
],
"changes": [
{
"version": "v11.0.0",
"pr-url": "https://github.com/nodejs/node/pull/22969",
"description": "Throws `ERR_OUT_OF_RANGE` instead of `ERR_INDEX_OUT_OF_RANGE`."
},
{
"version": "v10.0.0",
"pr-url": "https://github.com/nodejs/node/pull/18790",
"description": "Negative `end` values throw an `ERR_INDEX_OUT_OF_RANGE` error."
},
{
"version": "v10.0.0",
"pr-url": "https://github.com/nodejs/node/pull/18129",
"description": "Attempting to fill a non-zero length buffer with a zero length buffer triggers a thrown exception."
},
{
"version": "v10.0.0",
"pr-url": "https://github.com/nodejs/node/pull/17427",
"description": "Specifying an invalid string for `value` triggers a thrown exception."
},
{
"version": "v5.7.0",
"pr-url": "https://github.com/nodejs/node/pull/4935",
"description": "The `encoding` parameter is supported now."
}
]
},
"signatures": [
{
"return": {
"textRaw": "Returns: {Buffer} A reference to `buf`.",
"name": "return",
"type": "Buffer",
"desc": "A reference to `buf`."
},
"params": [
{
"textRaw": "`value` {string|Buffer|Uint8Array|integer} The value with which to fill `buf`.",
"name": "value",
"type": "string|Buffer|Uint8Array|integer",
"desc": "The value with which to fill `buf`."
},
{
"textRaw": "`offset` {integer} Number of bytes to skip before starting to fill `buf`. **Default:** `0`.",
"name": "offset",
"type": "integer",
"default": "`0`",
"desc": "Number of bytes to skip before starting to fill `buf`."
},
{
"textRaw": "`end` {integer} Where to stop filling `buf` (not inclusive). **Default:** [`buf.length`][].",
"name": "end",
"type": "integer",
"default": "[`buf.length`][]",
"desc": "Where to stop filling `buf` (not inclusive)."
},
{
"textRaw": "`encoding` {string} The encoding for `value` if `value` is a string. **Default:** `'utf8'`.",
"name": "encoding",
"type": "string",
"default": "`'utf8'`",
"desc": "The encoding for `value` if `value` is a string."
}
]
}
],
"desc": "Fills buf
with the specified value
. If the offset
and end
are not given,\nthe entire buf
will be filled:
// Fill a `Buffer` with the ASCII character 'h'.\n\nconst b = Buffer.allocUnsafe(50).fill('h');\n\nconsole.log(b.toString());\n// Prints: hhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhh\n
\nvalue
is coerced to a uint32
value if it is not a string, Buffer
, or\ninteger. If the resulting integer is greater than 255
(decimal), buf
will be\nfilled with value & 255
.
If the final write of a fill()
operation falls on a multi-byte character,\nthen only the bytes of that character that fit into buf
are written:
// Fill a `Buffer` with character that takes up two bytes in UTF-8.\n\nconsole.log(Buffer.allocUnsafe(5).fill('\\u0222'));\n// Prints: <Buffer c8 a2 c8 a2 c8>\n
\nIf value
contains invalid characters, it is truncated; if no valid\nfill data remains, an exception is thrown:
const buf = Buffer.allocUnsafe(5);\n\nconsole.log(buf.fill('a'));\n// Prints: <Buffer 61 61 61 61 61>\nconsole.log(buf.fill('aazz', 'hex'));\n// Prints: <Buffer aa aa aa aa aa>\nconsole.log(buf.fill('zz', 'hex'));\n// Throws an exception.\n
"
},
{
"textRaw": "`buf.includes(value[, byteOffset][, encoding])`",
"type": "method",
"name": "includes",
"meta": {
"added": [
"v5.3.0"
],
"changes": []
},
"signatures": [
{
"return": {
"textRaw": "Returns: {boolean} `true` if `value` was found in `buf`, `false` otherwise.",
"name": "return",
"type": "boolean",
"desc": "`true` if `value` was found in `buf`, `false` otherwise."
},
"params": [
{
"textRaw": "`value` {string|Buffer|Uint8Array|integer} What to search for.",
"name": "value",
"type": "string|Buffer|Uint8Array|integer",
"desc": "What to search for."
},
{
"textRaw": "`byteOffset` {integer} Where to begin searching in `buf`. If negative, then offset is calculated from the end of `buf`. **Default:** `0`.",
"name": "byteOffset",
"type": "integer",
"default": "`0`",
"desc": "Where to begin searching in `buf`. If negative, then offset is calculated from the end of `buf`."
},
{
"textRaw": "`encoding` {string} If `value` is a string, this is its encoding. **Default:** `'utf8'`.",
"name": "encoding",
"type": "string",
"default": "`'utf8'`",
"desc": "If `value` is a string, this is its encoding."
}
]
}
],
"desc": "Equivalent to buf.indexOf() !== -1
.
const buf = Buffer.from('this is a buffer');\n\nconsole.log(buf.includes('this'));\n// Prints: true\nconsole.log(buf.includes('is'));\n// Prints: true\nconsole.log(buf.includes(Buffer.from('a buffer')));\n// Prints: true\nconsole.log(buf.includes(97));\n// Prints: true (97 is the decimal ASCII value for 'a')\nconsole.log(buf.includes(Buffer.from('a buffer example')));\n// Prints: false\nconsole.log(buf.includes(Buffer.from('a buffer example').slice(0, 8)));\n// Prints: true\nconsole.log(buf.includes('this', 4));\n// Prints: false\n
"
},
{
"textRaw": "`buf.indexOf(value[, byteOffset][, encoding])`",
"type": "method",
"name": "indexOf",
"meta": {
"added": [
"v1.5.0"
],
"changes": [
{
"version": "v8.0.0",
"pr-url": "https://github.com/nodejs/node/pull/10236",
"description": "The `value` can now be a `Uint8Array`."
},
{
"version": "v5.7.0, v4.4.0",
"pr-url": "https://github.com/nodejs/node/pull/4803",
"description": "When `encoding` is being passed, the `byteOffset` parameter is no longer required."
}
]
},
"signatures": [
{
"return": {
"textRaw": "Returns: {integer} The index of the first occurrence of `value` in `buf`, or `-1` if `buf` does not contain `value`.",
"name": "return",
"type": "integer",
"desc": "The index of the first occurrence of `value` in `buf`, or `-1` if `buf` does not contain `value`."
},
"params": [
{
"textRaw": "`value` {string|Buffer|Uint8Array|integer} What to search for.",
"name": "value",
"type": "string|Buffer|Uint8Array|integer",
"desc": "What to search for."
},
{
"textRaw": "`byteOffset` {integer} Where to begin searching in `buf`. If negative, then offset is calculated from the end of `buf`. **Default:** `0`.",
"name": "byteOffset",
"type": "integer",
"default": "`0`",
"desc": "Where to begin searching in `buf`. If negative, then offset is calculated from the end of `buf`."
},
{
"textRaw": "`encoding` {string} If `value` is a string, this is the encoding used to determine the binary representation of the string that will be searched for in `buf`. **Default:** `'utf8'`.",
"name": "encoding",
"type": "string",
"default": "`'utf8'`",
"desc": "If `value` is a string, this is the encoding used to determine the binary representation of the string that will be searched for in `buf`."
}
]
}
],
"desc": "If value
is:
value
is interpreted according to the character encoding in\nencoding
.Buffer
or Uint8Array
, value
will be used in its entirety.\nTo compare a partial Buffer
, use buf.slice()
.value
will be interpreted as an unsigned 8-bit integer\nvalue between 0
and 255
.const buf = Buffer.from('this is a buffer');\n\nconsole.log(buf.indexOf('this'));\n// Prints: 0\nconsole.log(buf.indexOf('is'));\n// Prints: 2\nconsole.log(buf.indexOf(Buffer.from('a buffer')));\n// Prints: 8\nconsole.log(buf.indexOf(97));\n// Prints: 8 (97 is the decimal ASCII value for 'a')\nconsole.log(buf.indexOf(Buffer.from('a buffer example')));\n// Prints: -1\nconsole.log(buf.indexOf(Buffer.from('a buffer example').slice(0, 8)));\n// Prints: 8\n\nconst utf16Buffer = Buffer.from('\\u039a\\u0391\\u03a3\\u03a3\\u0395', 'utf16le');\n\nconsole.log(utf16Buffer.indexOf('\\u03a3', 0, 'utf16le'));\n// Prints: 4\nconsole.log(utf16Buffer.indexOf('\\u03a3', -4, 'utf16le'));\n// Prints: 6\n
\nIf value
is not a string, number, or Buffer
, this method will throw a\nTypeError
. If value
is a number, it will be coerced to a valid byte value,\nan integer between 0 and 255.
If byteOffset
is not a number, it will be coerced to a number. If the result\nof coercion is NaN
or 0
, then the entire buffer will be searched. This\nbehavior matches String#indexOf()
.
const b = Buffer.from('abcdef');\n\n// Passing a value that's a number, but not a valid byte.\n// Prints: 2, equivalent to searching for 99 or 'c'.\nconsole.log(b.indexOf(99.9));\nconsole.log(b.indexOf(256 + 99));\n\n// Passing a byteOffset that coerces to NaN or 0.\n// Prints: 1, searching the whole buffer.\nconsole.log(b.indexOf('b', undefined));\nconsole.log(b.indexOf('b', {}));\nconsole.log(b.indexOf('b', null));\nconsole.log(b.indexOf('b', []));\n
\nIf value
is an empty string or empty Buffer
and byteOffset
is less\nthan buf.length
, byteOffset
will be returned. If value
is empty and\nbyteOffset
is at least buf.length
, buf.length
will be returned.
Creates and returns an iterator of buf
keys (indices).
const buf = Buffer.from('buffer');\n\nfor (const key of buf.keys()) {\n console.log(key);\n}\n// Prints:\n// 0\n// 1\n// 2\n// 3\n// 4\n// 5\n
"
},
{
"textRaw": "`buf.lastIndexOf(value[, byteOffset][, encoding])`",
"type": "method",
"name": "lastIndexOf",
"meta": {
"added": [
"v6.0.0"
],
"changes": [
{
"version": "v8.0.0",
"pr-url": "https://github.com/nodejs/node/pull/10236",
"description": "The `value` can now be a `Uint8Array`."
}
]
},
"signatures": [
{
"return": {
"textRaw": "Returns: {integer} The index of the last occurrence of `value` in `buf`, or `-1` if `buf` does not contain `value`.",
"name": "return",
"type": "integer",
"desc": "The index of the last occurrence of `value` in `buf`, or `-1` if `buf` does not contain `value`."
},
"params": [
{
"textRaw": "`value` {string|Buffer|Uint8Array|integer} What to search for.",
"name": "value",
"type": "string|Buffer|Uint8Array|integer",
"desc": "What to search for."
},
{
"textRaw": "`byteOffset` {integer} Where to begin searching in `buf`. If negative, then offset is calculated from the end of `buf`. **Default:** `buf.length - 1`.",
"name": "byteOffset",
"type": "integer",
"default": "`buf.length - 1`",
"desc": "Where to begin searching in `buf`. If negative, then offset is calculated from the end of `buf`."
},
{
"textRaw": "`encoding` {string} If `value` is a string, this is the encoding used to determine the binary representation of the string that will be searched for in `buf`. **Default:** `'utf8'`.",
"name": "encoding",
"type": "string",
"default": "`'utf8'`",
"desc": "If `value` is a string, this is the encoding used to determine the binary representation of the string that will be searched for in `buf`."
}
]
}
],
"desc": "Identical to buf.indexOf()
, except the last occurrence of value
is found\nrather than the first occurrence.
const buf = Buffer.from('this buffer is a buffer');\n\nconsole.log(buf.lastIndexOf('this'));\n// Prints: 0\nconsole.log(buf.lastIndexOf('buffer'));\n// Prints: 17\nconsole.log(buf.lastIndexOf(Buffer.from('buffer')));\n// Prints: 17\nconsole.log(buf.lastIndexOf(97));\n// Prints: 15 (97 is the decimal ASCII value for 'a')\nconsole.log(buf.lastIndexOf(Buffer.from('yolo')));\n// Prints: -1\nconsole.log(buf.lastIndexOf('buffer', 5));\n// Prints: 5\nconsole.log(buf.lastIndexOf('buffer', 4));\n// Prints: -1\n\nconst utf16Buffer = Buffer.from('\\u039a\\u0391\\u03a3\\u03a3\\u0395', 'utf16le');\n\nconsole.log(utf16Buffer.lastIndexOf('\\u03a3', undefined, 'utf16le'));\n// Prints: 6\nconsole.log(utf16Buffer.lastIndexOf('\\u03a3', -5, 'utf16le'));\n// Prints: 4\n
\nIf value
is not a string, number, or Buffer
, this method will throw a\nTypeError
. If value
is a number, it will be coerced to a valid byte value,\nan integer between 0 and 255.
If byteOffset
is not a number, it will be coerced to a number. Any arguments\nthat coerce to NaN
, like {}
or undefined
, will search the whole buffer.\nThis behavior matches String#lastIndexOf()
.
const b = Buffer.from('abcdef');\n\n// Passing a value that's a number, but not a valid byte.\n// Prints: 2, equivalent to searching for 99 or 'c'.\nconsole.log(b.lastIndexOf(99.9));\nconsole.log(b.lastIndexOf(256 + 99));\n\n// Passing a byteOffset that coerces to NaN.\n// Prints: 1, searching the whole buffer.\nconsole.log(b.lastIndexOf('b', undefined));\nconsole.log(b.lastIndexOf('b', {}));\n\n// Passing a byteOffset that coerces to 0.\n// Prints: -1, equivalent to passing 0.\nconsole.log(b.lastIndexOf('b', null));\nconsole.log(b.lastIndexOf('b', []));\n
\nIf value
is an empty string or empty Buffer
, byteOffset
will be returned.
Reads a signed, big-endian 64-bit integer from buf
at the specified offset
.
Integers read from a Buffer
are interpreted as two's complement signed\nvalues.
Reads a signed, little-endian 64-bit integer from buf
at the specified\noffset
.
Integers read from a Buffer
are interpreted as two's complement signed\nvalues.
Reads an unsigned, big-endian 64-bit integer from buf
at the specified\noffset
.
const buf = Buffer.from([0x00, 0x00, 0x00, 0x00, 0xff, 0xff, 0xff, 0xff]);\n\nconsole.log(buf.readBigUInt64BE(0));\n// Prints: 4294967295n\n
"
},
{
"textRaw": "`buf.readBigUInt64LE([offset])`",
"type": "method",
"name": "readBigUInt64LE",
"meta": {
"added": [
"v12.0.0",
"v10.20.0"
],
"changes": []
},
"signatures": [
{
"return": {
"textRaw": "Returns: {bigint}",
"name": "return",
"type": "bigint"
},
"params": [
{
"textRaw": "`offset` {integer} Number of bytes to skip before starting to read. Must satisfy: `0 <= offset <= buf.length - 8`. **Default:** `0`.",
"name": "offset",
"type": "integer",
"default": "`0`",
"desc": "Number of bytes to skip before starting to read. Must satisfy: `0 <= offset <= buf.length - 8`."
}
]
}
],
"desc": "Reads an unsigned, little-endian 64-bit integer from buf
at the specified\noffset
.
const buf = Buffer.from([0x00, 0x00, 0x00, 0x00, 0xff, 0xff, 0xff, 0xff]);\n\nconsole.log(buf.readBigUInt64LE(0));\n// Prints: 18446744069414584320n\n
"
},
{
"textRaw": "`buf.readDoubleBE([offset])`",
"type": "method",
"name": "readDoubleBE",
"meta": {
"added": [
"v0.11.15"
],
"changes": [
{
"version": "v10.0.0",
"pr-url": "https://github.com/nodejs/node/pull/18395",
"description": "Removed `noAssert` and no implicit coercion of the offset to `uint32` anymore."
}
]
},
"signatures": [
{
"return": {
"textRaw": "Returns: {number}",
"name": "return",
"type": "number"
},
"params": [
{
"textRaw": "`offset` {integer} Number of bytes to skip before starting to read. Must satisfy `0 <= offset <= buf.length - 8`. **Default:** `0`.",
"name": "offset",
"type": "integer",
"default": "`0`",
"desc": "Number of bytes to skip before starting to read. Must satisfy `0 <= offset <= buf.length - 8`."
}
]
}
],
"desc": "Reads a 64-bit, big-endian double from buf
at the specified offset
.
const buf = Buffer.from([1, 2, 3, 4, 5, 6, 7, 8]);\n\nconsole.log(buf.readDoubleBE(0));\n// Prints: 8.20788039913184e-304\n
"
},
{
"textRaw": "`buf.readDoubleLE([offset])`",
"type": "method",
"name": "readDoubleLE",
"meta": {
"added": [
"v0.11.15"
],
"changes": [
{
"version": "v10.0.0",
"pr-url": "https://github.com/nodejs/node/pull/18395",
"description": "Removed `noAssert` and no implicit coercion of the offset to `uint32` anymore."
}
]
},
"signatures": [
{
"return": {
"textRaw": "Returns: {number}",
"name": "return",
"type": "number"
},
"params": [
{
"textRaw": "`offset` {integer} Number of bytes to skip before starting to read. Must satisfy `0 <= offset <= buf.length - 8`. **Default:** `0`.",
"name": "offset",
"type": "integer",
"default": "`0`",
"desc": "Number of bytes to skip before starting to read. Must satisfy `0 <= offset <= buf.length - 8`."
}
]
}
],
"desc": "Reads a 64-bit, little-endian double from buf
at the specified offset
.
const buf = Buffer.from([1, 2, 3, 4, 5, 6, 7, 8]);\n\nconsole.log(buf.readDoubleLE(0));\n// Prints: 5.447603722011605e-270\nconsole.log(buf.readDoubleLE(1));\n// Throws ERR_OUT_OF_RANGE.\n
"
},
{
"textRaw": "`buf.readFloatBE([offset])`",
"type": "method",
"name": "readFloatBE",
"meta": {
"added": [
"v0.11.15"
],
"changes": [
{
"version": "v10.0.0",
"pr-url": "https://github.com/nodejs/node/pull/18395",
"description": "Removed `noAssert` and no implicit coercion of the offset to `uint32` anymore."
}
]
},
"signatures": [
{
"return": {
"textRaw": "Returns: {number}",
"name": "return",
"type": "number"
},
"params": [
{
"textRaw": "`offset` {integer} Number of bytes to skip before starting to read. Must satisfy `0 <= offset <= buf.length - 4`. **Default:** `0`.",
"name": "offset",
"type": "integer",
"default": "`0`",
"desc": "Number of bytes to skip before starting to read. Must satisfy `0 <= offset <= buf.length - 4`."
}
]
}
],
"desc": "Reads a 32-bit, big-endian float from buf
at the specified offset
.
const buf = Buffer.from([1, 2, 3, 4]);\n\nconsole.log(buf.readFloatBE(0));\n// Prints: 2.387939260590663e-38\n
"
},
{
"textRaw": "`buf.readFloatLE([offset])`",
"type": "method",
"name": "readFloatLE",
"meta": {
"added": [
"v0.11.15"
],
"changes": [
{
"version": "v10.0.0",
"pr-url": "https://github.com/nodejs/node/pull/18395",
"description": "Removed `noAssert` and no implicit coercion of the offset to `uint32` anymore."
}
]
},
"signatures": [
{
"return": {
"textRaw": "Returns: {number}",
"name": "return",
"type": "number"
},
"params": [
{
"textRaw": "`offset` {integer} Number of bytes to skip before starting to read. Must satisfy `0 <= offset <= buf.length - 4`. **Default:** `0`.",
"name": "offset",
"type": "integer",
"default": "`0`",
"desc": "Number of bytes to skip before starting to read. Must satisfy `0 <= offset <= buf.length - 4`."
}
]
}
],
"desc": "Reads a 32-bit, little-endian float from buf
at the specified offset
.
const buf = Buffer.from([1, 2, 3, 4]);\n\nconsole.log(buf.readFloatLE(0));\n// Prints: 1.539989614439558e-36\nconsole.log(buf.readFloatLE(1));\n// Throws ERR_OUT_OF_RANGE.\n
"
},
{
"textRaw": "`buf.readInt8([offset])`",
"type": "method",
"name": "readInt8",
"meta": {
"added": [
"v0.5.0"
],
"changes": [
{
"version": "v10.0.0",
"pr-url": "https://github.com/nodejs/node/pull/18395",
"description": "Removed `noAssert` and no implicit coercion of the offset to `uint32` anymore."
}
]
},
"signatures": [
{
"return": {
"textRaw": "Returns: {integer}",
"name": "return",
"type": "integer"
},
"params": [
{
"textRaw": "`offset` {integer} Number of bytes to skip before starting to read. Must satisfy `0 <= offset <= buf.length - 1`. **Default:** `0`.",
"name": "offset",
"type": "integer",
"default": "`0`",
"desc": "Number of bytes to skip before starting to read. Must satisfy `0 <= offset <= buf.length - 1`."
}
]
}
],
"desc": "Reads a signed 8-bit integer from buf
at the specified offset
.
Integers read from a Buffer
are interpreted as two's complement signed values.
const buf = Buffer.from([-1, 5]);\n\nconsole.log(buf.readInt8(0));\n// Prints: -1\nconsole.log(buf.readInt8(1));\n// Prints: 5\nconsole.log(buf.readInt8(2));\n// Throws ERR_OUT_OF_RANGE.\n
"
},
{
"textRaw": "`buf.readInt16BE([offset])`",
"type": "method",
"name": "readInt16BE",
"meta": {
"added": [
"v0.5.5"
],
"changes": [
{
"version": "v10.0.0",
"pr-url": "https://github.com/nodejs/node/pull/18395",
"description": "Removed `noAssert` and no implicit coercion of the offset to `uint32` anymore."
}
]
},
"signatures": [
{
"return": {
"textRaw": "Returns: {integer}",
"name": "return",
"type": "integer"
},
"params": [
{
"textRaw": "`offset` {integer} Number of bytes to skip before starting to read. Must satisfy `0 <= offset <= buf.length - 2`. **Default:** `0`.",
"name": "offset",
"type": "integer",
"default": "`0`",
"desc": "Number of bytes to skip before starting to read. Must satisfy `0 <= offset <= buf.length - 2`."
}
]
}
],
"desc": "Reads a signed, big-endian 16-bit integer from buf
at the specified offset
.
Integers read from a Buffer
are interpreted as two's complement signed values.
const buf = Buffer.from([0, 5]);\n\nconsole.log(buf.readInt16BE(0));\n// Prints: 5\n
"
},
{
"textRaw": "`buf.readInt16LE([offset])`",
"type": "method",
"name": "readInt16LE",
"meta": {
"added": [
"v0.5.5"
],
"changes": [
{
"version": "v10.0.0",
"pr-url": "https://github.com/nodejs/node/pull/18395",
"description": "Removed `noAssert` and no implicit coercion of the offset to `uint32` anymore."
}
]
},
"signatures": [
{
"return": {
"textRaw": "Returns: {integer}",
"name": "return",
"type": "integer"
},
"params": [
{
"textRaw": "`offset` {integer} Number of bytes to skip before starting to read. Must satisfy `0 <= offset <= buf.length - 2`. **Default:** `0`.",
"name": "offset",
"type": "integer",
"default": "`0`",
"desc": "Number of bytes to skip before starting to read. Must satisfy `0 <= offset <= buf.length - 2`."
}
]
}
],
"desc": "Reads a signed, little-endian 16-bit integer from buf
at the specified\noffset
.
Integers read from a Buffer
are interpreted as two's complement signed values.
const buf = Buffer.from([0, 5]);\n\nconsole.log(buf.readInt16LE(0));\n// Prints: 1280\nconsole.log(buf.readInt16LE(1));\n// Throws ERR_OUT_OF_RANGE.\n
"
},
{
"textRaw": "`buf.readInt32BE([offset])`",
"type": "method",
"name": "readInt32BE",
"meta": {
"added": [
"v0.5.5"
],
"changes": [
{
"version": "v10.0.0",
"pr-url": "https://github.com/nodejs/node/pull/18395",
"description": "Removed `noAssert` and no implicit coercion of the offset to `uint32` anymore."
}
]
},
"signatures": [
{
"return": {
"textRaw": "Returns: {integer}",
"name": "return",
"type": "integer"
},
"params": [
{
"textRaw": "`offset` {integer} Number of bytes to skip before starting to read. Must satisfy `0 <= offset <= buf.length - 4`. **Default:** `0`.",
"name": "offset",
"type": "integer",
"default": "`0`",
"desc": "Number of bytes to skip before starting to read. Must satisfy `0 <= offset <= buf.length - 4`."
}
]
}
],
"desc": "Reads a signed, big-endian 32-bit integer from buf
at the specified offset
.
Integers read from a Buffer
are interpreted as two's complement signed values.
const buf = Buffer.from([0, 0, 0, 5]);\n\nconsole.log(buf.readInt32BE(0));\n// Prints: 5\n
"
},
{
"textRaw": "`buf.readInt32LE([offset])`",
"type": "method",
"name": "readInt32LE",
"meta": {
"added": [
"v0.5.5"
],
"changes": [
{
"version": "v10.0.0",
"pr-url": "https://github.com/nodejs/node/pull/18395",
"description": "Removed `noAssert` and no implicit coercion of the offset to `uint32` anymore."
}
]
},
"signatures": [
{
"return": {
"textRaw": "Returns: {integer}",
"name": "return",
"type": "integer"
},
"params": [
{
"textRaw": "`offset` {integer} Number of bytes to skip before starting to read. Must satisfy `0 <= offset <= buf.length - 4`. **Default:** `0`.",
"name": "offset",
"type": "integer",
"default": "`0`",
"desc": "Number of bytes to skip before starting to read. Must satisfy `0 <= offset <= buf.length - 4`."
}
]
}
],
"desc": "Reads a signed, little-endian 32-bit integer from buf
at the specified\noffset
.
Integers read from a Buffer
are interpreted as two's complement signed values.
const buf = Buffer.from([0, 0, 0, 5]);\n\nconsole.log(buf.readInt32LE(0));\n// Prints: 83886080\nconsole.log(buf.readInt32LE(1));\n// Throws ERR_OUT_OF_RANGE.\n
"
},
{
"textRaw": "`buf.readIntBE(offset, byteLength)`",
"type": "method",
"name": "readIntBE",
"meta": {
"added": [
"v0.11.15"
],
"changes": [
{
"version": "v10.0.0",
"pr-url": "https://github.com/nodejs/node/pull/18395",
"description": "Removed `noAssert` and no implicit coercion of the offset and `byteLength` to `uint32` anymore."
}
]
},
"signatures": [
{
"return": {
"textRaw": "Returns: {integer}",
"name": "return",
"type": "integer"
},
"params": [
{
"textRaw": "`offset` {integer} Number of bytes to skip before starting to read. Must satisfy `0 <= offset <= buf.length - byteLength`.",
"name": "offset",
"type": "integer",
"desc": "Number of bytes to skip before starting to read. Must satisfy `0 <= offset <= buf.length - byteLength`."
},
{
"textRaw": "`byteLength` {integer} Number of bytes to read. Must satisfy `0 < byteLength <= 6`.",
"name": "byteLength",
"type": "integer",
"desc": "Number of bytes to read. Must satisfy `0 < byteLength <= 6`."
}
]
}
],
"desc": "Reads byteLength
number of bytes from buf
at the specified offset
\nand interprets the result as a big-endian, two's complement signed value\nsupporting up to 48 bits of accuracy.
const buf = Buffer.from([0x12, 0x34, 0x56, 0x78, 0x90, 0xab]);\n\nconsole.log(buf.readIntBE(0, 6).toString(16));\n// Prints: 1234567890ab\nconsole.log(buf.readIntBE(1, 6).toString(16));\n// Throws ERR_OUT_OF_RANGE.\nconsole.log(buf.readIntBE(1, 0).toString(16));\n// Throws ERR_OUT_OF_RANGE.\n
"
},
{
"textRaw": "`buf.readIntLE(offset, byteLength)`",
"type": "method",
"name": "readIntLE",
"meta": {
"added": [
"v0.11.15"
],
"changes": [
{
"version": "v10.0.0",
"pr-url": "https://github.com/nodejs/node/pull/18395",
"description": "Removed `noAssert` and no implicit coercion of the offset and `byteLength` to `uint32` anymore."
}
]
},
"signatures": [
{
"return": {
"textRaw": "Returns: {integer}",
"name": "return",
"type": "integer"
},
"params": [
{
"textRaw": "`offset` {integer} Number of bytes to skip before starting to read. Must satisfy `0 <= offset <= buf.length - byteLength`.",
"name": "offset",
"type": "integer",
"desc": "Number of bytes to skip before starting to read. Must satisfy `0 <= offset <= buf.length - byteLength`."
},
{
"textRaw": "`byteLength` {integer} Number of bytes to read. Must satisfy `0 < byteLength <= 6`.",
"name": "byteLength",
"type": "integer",
"desc": "Number of bytes to read. Must satisfy `0 < byteLength <= 6`."
}
]
}
],
"desc": "Reads byteLength
number of bytes from buf
at the specified offset
\nand interprets the result as a little-endian, two's complement signed value\nsupporting up to 48 bits of accuracy.
const buf = Buffer.from([0x12, 0x34, 0x56, 0x78, 0x90, 0xab]);\n\nconsole.log(buf.readIntLE(0, 6).toString(16));\n// Prints: -546f87a9cbee\n
"
},
{
"textRaw": "`buf.readUInt8([offset])`",
"type": "method",
"name": "readUInt8",
"meta": {
"added": [
"v0.5.0"
],
"changes": [
{
"version": "v10.0.0",
"pr-url": "https://github.com/nodejs/node/pull/18395",
"description": "Removed `noAssert` and no implicit coercion of the offset to `uint32` anymore."
}
]
},
"signatures": [
{
"return": {
"textRaw": "Returns: {integer}",
"name": "return",
"type": "integer"
},
"params": [
{
"textRaw": "`offset` {integer} Number of bytes to skip before starting to read. Must satisfy `0 <= offset <= buf.length - 1`. **Default:** `0`.",
"name": "offset",
"type": "integer",
"default": "`0`",
"desc": "Number of bytes to skip before starting to read. Must satisfy `0 <= offset <= buf.length - 1`."
}
]
}
],
"desc": "Reads an unsigned 8-bit integer from buf
at the specified offset
.
const buf = Buffer.from([1, -2]);\n\nconsole.log(buf.readUInt8(0));\n// Prints: 1\nconsole.log(buf.readUInt8(1));\n// Prints: 254\nconsole.log(buf.readUInt8(2));\n// Throws ERR_OUT_OF_RANGE.\n
"
},
{
"textRaw": "`buf.readUInt16BE([offset])`",
"type": "method",
"name": "readUInt16BE",
"meta": {
"added": [
"v0.5.5"
],
"changes": [
{
"version": "v10.0.0",
"pr-url": "https://github.com/nodejs/node/pull/18395",
"description": "Removed `noAssert` and no implicit coercion of the offset to `uint32` anymore."
}
]
},
"signatures": [
{
"return": {
"textRaw": "Returns: {integer}",
"name": "return",
"type": "integer"
},
"params": [
{
"textRaw": "`offset` {integer} Number of bytes to skip before starting to read. Must satisfy `0 <= offset <= buf.length - 2`. **Default:** `0`.",
"name": "offset",
"type": "integer",
"default": "`0`",
"desc": "Number of bytes to skip before starting to read. Must satisfy `0 <= offset <= buf.length - 2`."
}
]
}
],
"desc": "Reads an unsigned, big-endian 16-bit integer from buf
at the specified\noffset
.
const buf = Buffer.from([0x12, 0x34, 0x56]);\n\nconsole.log(buf.readUInt16BE(0).toString(16));\n// Prints: 1234\nconsole.log(buf.readUInt16BE(1).toString(16));\n// Prints: 3456\n
"
},
{
"textRaw": "`buf.readUInt16LE([offset])`",
"type": "method",
"name": "readUInt16LE",
"meta": {
"added": [
"v0.5.5"
],
"changes": [
{
"version": "v10.0.0",
"pr-url": "https://github.com/nodejs/node/pull/18395",
"description": "Removed `noAssert` and no implicit coercion of the offset to `uint32` anymore."
}
]
},
"signatures": [
{
"return": {
"textRaw": "Returns: {integer}",
"name": "return",
"type": "integer"
},
"params": [
{
"textRaw": "`offset` {integer} Number of bytes to skip before starting to read. Must satisfy `0 <= offset <= buf.length - 2`. **Default:** `0`.",
"name": "offset",
"type": "integer",
"default": "`0`",
"desc": "Number of bytes to skip before starting to read. Must satisfy `0 <= offset <= buf.length - 2`."
}
]
}
],
"desc": "Reads an unsigned, little-endian 16-bit integer from buf
at the specified\noffset
.
const buf = Buffer.from([0x12, 0x34, 0x56]);\n\nconsole.log(buf.readUInt16LE(0).toString(16));\n// Prints: 3412\nconsole.log(buf.readUInt16LE(1).toString(16));\n// Prints: 5634\nconsole.log(buf.readUInt16LE(2).toString(16));\n// Throws ERR_OUT_OF_RANGE.\n
"
},
{
"textRaw": "`buf.readUInt32BE([offset])`",
"type": "method",
"name": "readUInt32BE",
"meta": {
"added": [
"v0.5.5"
],
"changes": [
{
"version": "v10.0.0",
"pr-url": "https://github.com/nodejs/node/pull/18395",
"description": "Removed `noAssert` and no implicit coercion of the offset to `uint32` anymore."
}
]
},
"signatures": [
{
"return": {
"textRaw": "Returns: {integer}",
"name": "return",
"type": "integer"
},
"params": [
{
"textRaw": "`offset` {integer} Number of bytes to skip before starting to read. Must satisfy `0 <= offset <= buf.length - 4`. **Default:** `0`.",
"name": "offset",
"type": "integer",
"default": "`0`",
"desc": "Number of bytes to skip before starting to read. Must satisfy `0 <= offset <= buf.length - 4`."
}
]
}
],
"desc": "Reads an unsigned, big-endian 32-bit integer from buf
at the specified\noffset
.
const buf = Buffer.from([0x12, 0x34, 0x56, 0x78]);\n\nconsole.log(buf.readUInt32BE(0).toString(16));\n// Prints: 12345678\n
"
},
{
"textRaw": "`buf.readUInt32LE([offset])`",
"type": "method",
"name": "readUInt32LE",
"meta": {
"added": [
"v0.5.5"
],
"changes": [
{
"version": "v10.0.0",
"pr-url": "https://github.com/nodejs/node/pull/18395",
"description": "Removed `noAssert` and no implicit coercion of the offset to `uint32` anymore."
}
]
},
"signatures": [
{
"return": {
"textRaw": "Returns: {integer}",
"name": "return",
"type": "integer"
},
"params": [
{
"textRaw": "`offset` {integer} Number of bytes to skip before starting to read. Must satisfy `0 <= offset <= buf.length - 4`. **Default:** `0`.",
"name": "offset",
"type": "integer",
"default": "`0`",
"desc": "Number of bytes to skip before starting to read. Must satisfy `0 <= offset <= buf.length - 4`."
}
]
}
],
"desc": "Reads an unsigned, little-endian 32-bit integer from buf
at the specified\noffset
.
const buf = Buffer.from([0x12, 0x34, 0x56, 0x78]);\n\nconsole.log(buf.readUInt32LE(0).toString(16));\n// Prints: 78563412\nconsole.log(buf.readUInt32LE(1).toString(16));\n// Throws ERR_OUT_OF_RANGE.\n
"
},
{
"textRaw": "`buf.readUIntBE(offset, byteLength)`",
"type": "method",
"name": "readUIntBE",
"meta": {
"added": [
"v0.11.15"
],
"changes": [
{
"version": "v10.0.0",
"pr-url": "https://github.com/nodejs/node/pull/18395",
"description": "Removed `noAssert` and no implicit coercion of the offset and `byteLength` to `uint32` anymore."
}
]
},
"signatures": [
{
"return": {
"textRaw": "Returns: {integer}",
"name": "return",
"type": "integer"
},
"params": [
{
"textRaw": "`offset` {integer} Number of bytes to skip before starting to read. Must satisfy `0 <= offset <= buf.length - byteLength`.",
"name": "offset",
"type": "integer",
"desc": "Number of bytes to skip before starting to read. Must satisfy `0 <= offset <= buf.length - byteLength`."
},
{
"textRaw": "`byteLength` {integer} Number of bytes to read. Must satisfy `0 < byteLength <= 6`.",
"name": "byteLength",
"type": "integer",
"desc": "Number of bytes to read. Must satisfy `0 < byteLength <= 6`."
}
]
}
],
"desc": "Reads byteLength
number of bytes from buf
at the specified offset
\nand interprets the result as an unsigned big-endian integer supporting\nup to 48 bits of accuracy.
const buf = Buffer.from([0x12, 0x34, 0x56, 0x78, 0x90, 0xab]);\n\nconsole.log(buf.readUIntBE(0, 6).toString(16));\n// Prints: 1234567890ab\nconsole.log(buf.readUIntBE(1, 6).toString(16));\n// Throws ERR_OUT_OF_RANGE.\n
"
},
{
"textRaw": "`buf.readUIntLE(offset, byteLength)`",
"type": "method",
"name": "readUIntLE",
"meta": {
"added": [
"v0.11.15"
],
"changes": [
{
"version": "v10.0.0",
"pr-url": "https://github.com/nodejs/node/pull/18395",
"description": "Removed `noAssert` and no implicit coercion of the offset and `byteLength` to `uint32` anymore."
}
]
},
"signatures": [
{
"return": {
"textRaw": "Returns: {integer}",
"name": "return",
"type": "integer"
},
"params": [
{
"textRaw": "`offset` {integer} Number of bytes to skip before starting to read. Must satisfy `0 <= offset <= buf.length - byteLength`.",
"name": "offset",
"type": "integer",
"desc": "Number of bytes to skip before starting to read. Must satisfy `0 <= offset <= buf.length - byteLength`."
},
{
"textRaw": "`byteLength` {integer} Number of bytes to read. Must satisfy `0 < byteLength <= 6`.",
"name": "byteLength",
"type": "integer",
"desc": "Number of bytes to read. Must satisfy `0 < byteLength <= 6`."
}
]
}
],
"desc": "Reads byteLength
number of bytes from buf
at the specified offset
\nand interprets the result as an unsigned, little-endian integer supporting\nup to 48 bits of accuracy.
const buf = Buffer.from([0x12, 0x34, 0x56, 0x78, 0x90, 0xab]);\n\nconsole.log(buf.readUIntLE(0, 6).toString(16));\n// Prints: ab9078563412\n
"
},
{
"textRaw": "`buf.subarray([start[, end]])`",
"type": "method",
"name": "subarray",
"meta": {
"added": [
"v3.0.0"
],
"changes": []
},
"signatures": [
{
"return": {
"textRaw": "Returns: {Buffer}",
"name": "return",
"type": "Buffer"
},
"params": [
{
"textRaw": "`start` {integer} Where the new `Buffer` will start. **Default:** `0`.",
"name": "start",
"type": "integer",
"default": "`0`",
"desc": "Where the new `Buffer` will start."
},
{
"textRaw": "`end` {integer} Where the new `Buffer` will end (not inclusive). **Default:** [`buf.length`][].",
"name": "end",
"type": "integer",
"default": "[`buf.length`][]",
"desc": "Where the new `Buffer` will end (not inclusive)."
}
]
}
],
"desc": "Returns a new Buffer
that references the same memory as the original, but\noffset and cropped by the start
and end
indices.
Specifying end
greater than buf.length
will return the same result as\nthat of end
equal to buf.length
.
This method is inherited from TypedArray#subarray()
.
Modifying the new Buffer
slice will modify the memory in the original Buffer
\nbecause the allocated memory of the two objects overlap.
// Create a `Buffer` with the ASCII alphabet, take a slice, and modify one byte\n// from the original `Buffer`.\n\nconst buf1 = Buffer.allocUnsafe(26);\n\nfor (let i = 0; i < 26; i++) {\n // 97 is the decimal ASCII value for 'a'.\n buf1[i] = i + 97;\n}\n\nconst buf2 = buf1.subarray(0, 3);\n\nconsole.log(buf2.toString('ascii', 0, buf2.length));\n// Prints: abc\n\nbuf1[0] = 33;\n\nconsole.log(buf2.toString('ascii', 0, buf2.length));\n// Prints: !bc\n
\nSpecifying negative indexes causes the slice to be generated relative to the\nend of buf
rather than the beginning.
const buf = Buffer.from('buffer');\n\nconsole.log(buf.subarray(-6, -1).toString());\n// Prints: buffe\n// (Equivalent to buf.subarray(0, 5).)\n\nconsole.log(buf.subarray(-6, -2).toString());\n// Prints: buff\n// (Equivalent to buf.subarray(0, 4).)\n\nconsole.log(buf.subarray(-5, -2).toString());\n// Prints: uff\n// (Equivalent to buf.subarray(1, 4).)\n
"
},
{
"textRaw": "`buf.slice([start[, end]])`",
"type": "method",
"name": "slice",
"meta": {
"added": [
"v0.3.0"
],
"changes": [
{
"version": "v7.1.0, v6.9.2",
"pr-url": "https://github.com/nodejs/node/pull/9341",
"description": "Coercing the offsets to integers now handles values outside the 32-bit integer range properly."
},
{
"version": "v7.0.0",
"pr-url": "https://github.com/nodejs/node/pull/9101",
"description": "All offsets are now coerced to integers before doing any calculations with them."
}
]
},
"signatures": [
{
"return": {
"textRaw": "Returns: {Buffer}",
"name": "return",
"type": "Buffer"
},
"params": [
{
"textRaw": "`start` {integer} Where the new `Buffer` will start. **Default:** `0`.",
"name": "start",
"type": "integer",
"default": "`0`",
"desc": "Where the new `Buffer` will start."
},
{
"textRaw": "`end` {integer} Where the new `Buffer` will end (not inclusive). **Default:** [`buf.length`][].",
"name": "end",
"type": "integer",
"default": "[`buf.length`][]",
"desc": "Where the new `Buffer` will end (not inclusive)."
}
]
}
],
"desc": "Returns a new Buffer
that references the same memory as the original, but\noffset and cropped by the start
and end
indices.
This is the same behavior as buf.subarray()
.
This method is not compatible with the Uint8Array.prototype.slice()
,\nwhich is a superclass of Buffer
. To copy the slice, use\nUint8Array.prototype.slice()
.
const buf = Buffer.from('buffer');\n\nconst copiedBuf = Uint8Array.prototype.slice.call(buf);\ncopiedBuf[0]++;\nconsole.log(copiedBuf.toString());\n// Prints: cuffer\n\nconsole.log(buf.toString());\n// Prints: buffer\n
"
},
{
"textRaw": "`buf.swap16()`",
"type": "method",
"name": "swap16",
"meta": {
"added": [
"v5.10.0"
],
"changes": []
},
"signatures": [
{
"return": {
"textRaw": "Returns: {Buffer} A reference to `buf`.",
"name": "return",
"type": "Buffer",
"desc": "A reference to `buf`."
},
"params": []
}
],
"desc": "Interprets buf
as an array of unsigned 16-bit integers and swaps the\nbyte order in-place. Throws ERR_INVALID_BUFFER_SIZE
if buf.length
\nis not a multiple of 2.
const buf1 = Buffer.from([0x1, 0x2, 0x3, 0x4, 0x5, 0x6, 0x7, 0x8]);\n\nconsole.log(buf1);\n// Prints: <Buffer 01 02 03 04 05 06 07 08>\n\nbuf1.swap16();\n\nconsole.log(buf1);\n// Prints: <Buffer 02 01 04 03 06 05 08 07>\n\nconst buf2 = Buffer.from([0x1, 0x2, 0x3]);\n\nbuf2.swap16();\n// Throws ERR_INVALID_BUFFER_SIZE.\n
\nOne convenient use of buf.swap16()
is to perform a fast in-place conversion\nbetween UTF-16 little-endian and UTF-16 big-endian:
const buf = Buffer.from('This is little-endian UTF-16', 'utf16le');\nbuf.swap16(); // Convert to big-endian UTF-16 text.\n
"
},
{
"textRaw": "`buf.swap32()`",
"type": "method",
"name": "swap32",
"meta": {
"added": [
"v5.10.0"
],
"changes": []
},
"signatures": [
{
"return": {
"textRaw": "Returns: {Buffer} A reference to `buf`.",
"name": "return",
"type": "Buffer",
"desc": "A reference to `buf`."
},
"params": []
}
],
"desc": "Interprets buf
as an array of unsigned 32-bit integers and swaps the\nbyte order in-place. Throws ERR_INVALID_BUFFER_SIZE
if buf.length
\nis not a multiple of 4.
const buf1 = Buffer.from([0x1, 0x2, 0x3, 0x4, 0x5, 0x6, 0x7, 0x8]);\n\nconsole.log(buf1);\n// Prints: <Buffer 01 02 03 04 05 06 07 08>\n\nbuf1.swap32();\n\nconsole.log(buf1);\n// Prints: <Buffer 04 03 02 01 08 07 06 05>\n\nconst buf2 = Buffer.from([0x1, 0x2, 0x3]);\n\nbuf2.swap32();\n// Throws ERR_INVALID_BUFFER_SIZE.\n
"
},
{
"textRaw": "`buf.swap64()`",
"type": "method",
"name": "swap64",
"meta": {
"added": [
"v6.3.0"
],
"changes": []
},
"signatures": [
{
"return": {
"textRaw": "Returns: {Buffer} A reference to `buf`.",
"name": "return",
"type": "Buffer",
"desc": "A reference to `buf`."
},
"params": []
}
],
"desc": "Interprets buf
as an array of 64-bit numbers and swaps byte order in-place.\nThrows ERR_INVALID_BUFFER_SIZE
if buf.length
is not a multiple of 8.
const buf1 = Buffer.from([0x1, 0x2, 0x3, 0x4, 0x5, 0x6, 0x7, 0x8]);\n\nconsole.log(buf1);\n// Prints: <Buffer 01 02 03 04 05 06 07 08>\n\nbuf1.swap64();\n\nconsole.log(buf1);\n// Prints: <Buffer 08 07 06 05 04 03 02 01>\n\nconst buf2 = Buffer.from([0x1, 0x2, 0x3]);\n\nbuf2.swap64();\n// Throws ERR_INVALID_BUFFER_SIZE.\n
"
},
{
"textRaw": "`buf.toJSON()`",
"type": "method",
"name": "toJSON",
"meta": {
"added": [
"v0.9.2"
],
"changes": []
},
"signatures": [
{
"return": {
"textRaw": "Returns: {Object}",
"name": "return",
"type": "Object"
},
"params": []
}
],
"desc": "Returns a JSON representation of buf
. JSON.stringify()
implicitly calls\nthis function when stringifying a Buffer
instance.
Buffer.from()
accepts objects in the format returned from this method.\nIn particular, Buffer.from(buf.toJSON())
works like Buffer.from(buf)
.
const buf = Buffer.from([0x1, 0x2, 0x3, 0x4, 0x5]);\nconst json = JSON.stringify(buf);\n\nconsole.log(json);\n// Prints: {\"type\":\"Buffer\",\"data\":[1,2,3,4,5]}\n\nconst copy = JSON.parse(json, (key, value) => {\n return value && value.type === 'Buffer' ?\n Buffer.from(value) :\n value;\n});\n\nconsole.log(copy);\n// Prints: <Buffer 01 02 03 04 05>\n
"
},
{
"textRaw": "`buf.toString([encoding[, start[, end]]])`",
"type": "method",
"name": "toString",
"meta": {
"added": [
"v0.1.90"
],
"changes": []
},
"signatures": [
{
"return": {
"textRaw": "Returns: {string}",
"name": "return",
"type": "string"
},
"params": [
{
"textRaw": "`encoding` {string} The character encoding to use. **Default:** `'utf8'`.",
"name": "encoding",
"type": "string",
"default": "`'utf8'`",
"desc": "The character encoding to use."
},
{
"textRaw": "`start` {integer} The byte offset to start decoding at. **Default:** `0`.",
"name": "start",
"type": "integer",
"default": "`0`",
"desc": "The byte offset to start decoding at."
},
{
"textRaw": "`end` {integer} The byte offset to stop decoding at (not inclusive). **Default:** [`buf.length`][].",
"name": "end",
"type": "integer",
"default": "[`buf.length`][]",
"desc": "The byte offset to stop decoding at (not inclusive)."
}
]
}
],
"desc": "Decodes buf
to a string according to the specified character encoding in\nencoding
. start
and end
may be passed to decode only a subset of buf
.
If encoding
is 'utf8'
and a byte sequence in the input is not valid UTF-8,\nthen each invalid byte is replaced with the replacement character U+FFFD
.
The maximum length of a string instance (in UTF-16 code units) is available\nas buffer.constants.MAX_STRING_LENGTH
.
const buf1 = Buffer.allocUnsafe(26);\n\nfor (let i = 0; i < 26; i++) {\n // 97 is the decimal ASCII value for 'a'.\n buf1[i] = i + 97;\n}\n\nconsole.log(buf1.toString('utf8'));\n// Prints: abcdefghijklmnopqrstuvwxyz\nconsole.log(buf1.toString('utf8', 0, 5));\n// Prints: abcde\n\nconst buf2 = Buffer.from('tést');\n\nconsole.log(buf2.toString('hex'));\n// Prints: 74c3a97374\nconsole.log(buf2.toString('utf8', 0, 3));\n// Prints: té\nconsole.log(buf2.toString(undefined, 0, 3));\n// Prints: té\n
"
},
{
"textRaw": "`buf.values()`",
"type": "method",
"name": "values",
"meta": {
"added": [
"v1.1.0"
],
"changes": []
},
"signatures": [
{
"return": {
"textRaw": "Returns: {Iterator}",
"name": "return",
"type": "Iterator"
},
"params": []
}
],
"desc": "Creates and returns an iterator for buf
values (bytes). This function is\ncalled automatically when a Buffer
is used in a for..of
statement.
const buf = Buffer.from('buffer');\n\nfor (const value of buf.values()) {\n console.log(value);\n}\n// Prints:\n// 98\n// 117\n// 102\n// 102\n// 101\n// 114\n\nfor (const value of buf) {\n console.log(value);\n}\n// Prints:\n// 98\n// 117\n// 102\n// 102\n// 101\n// 114\n
"
},
{
"textRaw": "`buf.write(string[, offset[, length]][, encoding])`",
"type": "method",
"name": "write",
"meta": {
"added": [
"v0.1.90"
],
"changes": []
},
"signatures": [
{
"return": {
"textRaw": "Returns: {integer} Number of bytes written.",
"name": "return",
"type": "integer",
"desc": "Number of bytes written."
},
"params": [
{
"textRaw": "`string` {string} String to write to `buf`.",
"name": "string",
"type": "string",
"desc": "String to write to `buf`."
},
{
"textRaw": "`offset` {integer} Number of bytes to skip before starting to write `string`. **Default:** `0`.",
"name": "offset",
"type": "integer",
"default": "`0`",
"desc": "Number of bytes to skip before starting to write `string`."
},
{
"textRaw": "`length` {integer} Maximum number of bytes to write (written bytes will not exceed `buf.length - offset`). **Default:** `buf.length - offset`.",
"name": "length",
"type": "integer",
"default": "`buf.length - offset`",
"desc": "Maximum number of bytes to write (written bytes will not exceed `buf.length - offset`)."
},
{
"textRaw": "`encoding` {string} The character encoding of `string`. **Default:** `'utf8'`.",
"name": "encoding",
"type": "string",
"default": "`'utf8'`",
"desc": "The character encoding of `string`."
}
]
}
],
"desc": "Writes string
to buf
at offset
according to the character encoding in\nencoding
. The length
parameter is the number of bytes to write. If buf
did\nnot contain enough space to fit the entire string, only part of string
will be\nwritten. However, partially encoded characters will not be written.
const buf = Buffer.alloc(256);\n\nconst len = buf.write('\\u00bd + \\u00bc = \\u00be', 0);\n\nconsole.log(`${len} bytes: ${buf.toString('utf8', 0, len)}`);\n// Prints: 12 bytes: ½ + ¼ = ¾\n\nconst buffer = Buffer.alloc(10);\n\nconst length = buffer.write('abcd', 8);\n\nconsole.log(`${length} bytes: ${buffer.toString('utf8', 8, 10)}`);\n// Prints: 2 bytes : ab\n
"
},
{
"textRaw": "`buf.writeBigInt64BE(value[, offset])`",
"type": "method",
"name": "writeBigInt64BE",
"meta": {
"added": [
"v12.0.0",
"v10.20.0"
],
"changes": []
},
"signatures": [
{
"return": {
"textRaw": "Returns: {integer} `offset` plus the number of bytes written.",
"name": "return",
"type": "integer",
"desc": "`offset` plus the number of bytes written."
},
"params": [
{
"textRaw": "`value` {bigint} Number to be written to `buf`.",
"name": "value",
"type": "bigint",
"desc": "Number to be written to `buf`."
},
{
"textRaw": "`offset` {integer} Number of bytes to skip before starting to write. Must satisfy: `0 <= offset <= buf.length - 8`. **Default:** `0`.",
"name": "offset",
"type": "integer",
"default": "`0`",
"desc": "Number of bytes to skip before starting to write. Must satisfy: `0 <= offset <= buf.length - 8`."
}
]
}
],
"desc": "Writes value
to buf
at the specified offset
as big-endian.
value
is interpreted and written as a two's complement signed integer.
const buf = Buffer.allocUnsafe(8);\n\nbuf.writeBigInt64BE(0x0102030405060708n, 0);\n\nconsole.log(buf);\n// Prints: <Buffer 01 02 03 04 05 06 07 08>\n
"
},
{
"textRaw": "`buf.writeBigInt64LE(value[, offset])`",
"type": "method",
"name": "writeBigInt64LE",
"meta": {
"added": [
"v12.0.0",
"v10.20.0"
],
"changes": []
},
"signatures": [
{
"return": {
"textRaw": "Returns: {integer} `offset` plus the number of bytes written.",
"name": "return",
"type": "integer",
"desc": "`offset` plus the number of bytes written."
},
"params": [
{
"textRaw": "`value` {bigint} Number to be written to `buf`.",
"name": "value",
"type": "bigint",
"desc": "Number to be written to `buf`."
},
{
"textRaw": "`offset` {integer} Number of bytes to skip before starting to write. Must satisfy: `0 <= offset <= buf.length - 8`. **Default:** `0`.",
"name": "offset",
"type": "integer",
"default": "`0`",
"desc": "Number of bytes to skip before starting to write. Must satisfy: `0 <= offset <= buf.length - 8`."
}
]
}
],
"desc": "Writes value
to buf
at the specified offset
as little-endian.
value
is interpreted and written as a two's complement signed integer.
const buf = Buffer.allocUnsafe(8);\n\nbuf.writeBigInt64LE(0x0102030405060708n, 0);\n\nconsole.log(buf);\n// Prints: <Buffer 08 07 06 05 04 03 02 01>\n
"
},
{
"textRaw": "`buf.writeBigUInt64BE(value[, offset])`",
"type": "method",
"name": "writeBigUInt64BE",
"meta": {
"added": [
"v12.0.0",
"v10.20.0"
],
"changes": []
},
"signatures": [
{
"return": {
"textRaw": "Returns: {integer} `offset` plus the number of bytes written.",
"name": "return",
"type": "integer",
"desc": "`offset` plus the number of bytes written."
},
"params": [
{
"textRaw": "`value` {bigint} Number to be written to `buf`.",
"name": "value",
"type": "bigint",
"desc": "Number to be written to `buf`."
},
{
"textRaw": "`offset` {integer} Number of bytes to skip before starting to write. Must satisfy: `0 <= offset <= buf.length - 8`. **Default:** `0`.",
"name": "offset",
"type": "integer",
"default": "`0`",
"desc": "Number of bytes to skip before starting to write. Must satisfy: `0 <= offset <= buf.length - 8`."
}
]
}
],
"desc": "Writes value
to buf
at the specified offset
as big-endian.
const buf = Buffer.allocUnsafe(8);\n\nbuf.writeBigUInt64BE(0xdecafafecacefaden, 0);\n\nconsole.log(buf);\n// Prints: <Buffer de ca fa fe ca ce fa de>\n
"
},
{
"textRaw": "`buf.writeBigUInt64LE(value[, offset])`",
"type": "method",
"name": "writeBigUInt64LE",
"meta": {
"added": [
"v12.0.0",
"v10.20.0"
],
"changes": []
},
"signatures": [
{
"return": {
"textRaw": "Returns: {integer} `offset` plus the number of bytes written.",
"name": "return",
"type": "integer",
"desc": "`offset` plus the number of bytes written."
},
"params": [
{
"textRaw": "`value` {bigint} Number to be written to `buf`.",
"name": "value",
"type": "bigint",
"desc": "Number to be written to `buf`."
},
{
"textRaw": "`offset` {integer} Number of bytes to skip before starting to write. Must satisfy: `0 <= offset <= buf.length - 8`. **Default:** `0`.",
"name": "offset",
"type": "integer",
"default": "`0`",
"desc": "Number of bytes to skip before starting to write. Must satisfy: `0 <= offset <= buf.length - 8`."
}
]
}
],
"desc": "Writes value
to buf
at the specified offset
as little-endian
const buf = Buffer.allocUnsafe(8);\n\nbuf.writeBigUInt64LE(0xdecafafecacefaden, 0);\n\nconsole.log(buf);\n// Prints: <Buffer de fa ce ca fe fa ca de>\n
"
},
{
"textRaw": "`buf.writeDoubleBE(value[, offset])`",
"type": "method",
"name": "writeDoubleBE",
"meta": {
"added": [
"v0.11.15"
],
"changes": [
{
"version": "v10.0.0",
"pr-url": "https://github.com/nodejs/node/pull/18395",
"description": "Removed `noAssert` and no implicit coercion of the offset to `uint32` anymore."
}
]
},
"signatures": [
{
"return": {
"textRaw": "Returns: {integer} `offset` plus the number of bytes written.",
"name": "return",
"type": "integer",
"desc": "`offset` plus the number of bytes written."
},
"params": [
{
"textRaw": "`value` {number} Number to be written to `buf`.",
"name": "value",
"type": "number",
"desc": "Number to be written to `buf`."
},
{
"textRaw": "`offset` {integer} Number of bytes to skip before starting to write. Must satisfy `0 <= offset <= buf.length - 8`. **Default:** `0`.",
"name": "offset",
"type": "integer",
"default": "`0`",
"desc": "Number of bytes to skip before starting to write. Must satisfy `0 <= offset <= buf.length - 8`."
}
]
}
],
"desc": "Writes value
to buf
at the specified offset
as big-endian. The value
\nmust be a JavaScript number. Behavior is undefined when value
is anything\nother than a JavaScript number.
const buf = Buffer.allocUnsafe(8);\n\nbuf.writeDoubleBE(123.456, 0);\n\nconsole.log(buf);\n// Prints: <Buffer 40 5e dd 2f 1a 9f be 77>\n
"
},
{
"textRaw": "`buf.writeDoubleLE(value[, offset])`",
"type": "method",
"name": "writeDoubleLE",
"meta": {
"added": [
"v0.11.15"
],
"changes": [
{
"version": "v10.0.0",
"pr-url": "https://github.com/nodejs/node/pull/18395",
"description": "Removed `noAssert` and no implicit coercion of the offset to `uint32` anymore."
}
]
},
"signatures": [
{
"return": {
"textRaw": "Returns: {integer} `offset` plus the number of bytes written.",
"name": "return",
"type": "integer",
"desc": "`offset` plus the number of bytes written."
},
"params": [
{
"textRaw": "`value` {number} Number to be written to `buf`.",
"name": "value",
"type": "number",
"desc": "Number to be written to `buf`."
},
{
"textRaw": "`offset` {integer} Number of bytes to skip before starting to write. Must satisfy `0 <= offset <= buf.length - 8`. **Default:** `0`.",
"name": "offset",
"type": "integer",
"default": "`0`",
"desc": "Number of bytes to skip before starting to write. Must satisfy `0 <= offset <= buf.length - 8`."
}
]
}
],
"desc": "Writes value
to buf
at the specified offset
as little-endian. The value
\nmust be a JavaScript number. Behavior is undefined when value
is anything\nother than a JavaScript number.
const buf = Buffer.allocUnsafe(8);\n\nbuf.writeDoubleLE(123.456, 0);\n\nconsole.log(buf);\n// Prints: <Buffer 77 be 9f 1a 2f dd 5e 40>\n
"
},
{
"textRaw": "`buf.writeFloatBE(value[, offset])`",
"type": "method",
"name": "writeFloatBE",
"meta": {
"added": [
"v0.11.15"
],
"changes": [
{
"version": "v10.0.0",
"pr-url": "https://github.com/nodejs/node/pull/18395",
"description": "Removed `noAssert` and no implicit coercion of the offset to `uint32` anymore."
}
]
},
"signatures": [
{
"return": {
"textRaw": "Returns: {integer} `offset` plus the number of bytes written.",
"name": "return",
"type": "integer",
"desc": "`offset` plus the number of bytes written."
},
"params": [
{
"textRaw": "`value` {number} Number to be written to `buf`.",
"name": "value",
"type": "number",
"desc": "Number to be written to `buf`."
},
{
"textRaw": "`offset` {integer} Number of bytes to skip before starting to write. Must satisfy `0 <= offset <= buf.length - 4`. **Default:** `0`.",
"name": "offset",
"type": "integer",
"default": "`0`",
"desc": "Number of bytes to skip before starting to write. Must satisfy `0 <= offset <= buf.length - 4`."
}
]
}
],
"desc": "Writes value
to buf
at the specified offset
as big-endian. Behavior is\nundefined when value
is anything other than a JavaScript number.
const buf = Buffer.allocUnsafe(4);\n\nbuf.writeFloatBE(0xcafebabe, 0);\n\nconsole.log(buf);\n// Prints: <Buffer 4f 4a fe bb>\n
"
},
{
"textRaw": "`buf.writeFloatLE(value[, offset])`",
"type": "method",
"name": "writeFloatLE",
"meta": {
"added": [
"v0.11.15"
],
"changes": [
{
"version": "v10.0.0",
"pr-url": "https://github.com/nodejs/node/pull/18395",
"description": "Removed `noAssert` and no implicit coercion of the offset to `uint32` anymore."
}
]
},
"signatures": [
{
"return": {
"textRaw": "Returns: {integer} `offset` plus the number of bytes written.",
"name": "return",
"type": "integer",
"desc": "`offset` plus the number of bytes written."
},
"params": [
{
"textRaw": "`value` {number} Number to be written to `buf`.",
"name": "value",
"type": "number",
"desc": "Number to be written to `buf`."
},
{
"textRaw": "`offset` {integer} Number of bytes to skip before starting to write. Must satisfy `0 <= offset <= buf.length - 4`. **Default:** `0`.",
"name": "offset",
"type": "integer",
"default": "`0`",
"desc": "Number of bytes to skip before starting to write. Must satisfy `0 <= offset <= buf.length - 4`."
}
]
}
],
"desc": "Writes value
to buf
at the specified offset
as little-endian. Behavior is\nundefined when value
is anything other than a JavaScript number.
const buf = Buffer.allocUnsafe(4);\n\nbuf.writeFloatLE(0xcafebabe, 0);\n\nconsole.log(buf);\n// Prints: <Buffer bb fe 4a 4f>\n
"
},
{
"textRaw": "`buf.writeInt8(value[, offset])`",
"type": "method",
"name": "writeInt8",
"meta": {
"added": [
"v0.5.0"
],
"changes": [
{
"version": "v10.0.0",
"pr-url": "https://github.com/nodejs/node/pull/18395",
"description": "Removed `noAssert` and no implicit coercion of the offset to `uint32` anymore."
}
]
},
"signatures": [
{
"return": {
"textRaw": "Returns: {integer} `offset` plus the number of bytes written.",
"name": "return",
"type": "integer",
"desc": "`offset` plus the number of bytes written."
},
"params": [
{
"textRaw": "`value` {integer} Number to be written to `buf`.",
"name": "value",
"type": "integer",
"desc": "Number to be written to `buf`."
},
{
"textRaw": "`offset` {integer} Number of bytes to skip before starting to write. Must satisfy `0 <= offset <= buf.length - 1`. **Default:** `0`.",
"name": "offset",
"type": "integer",
"default": "`0`",
"desc": "Number of bytes to skip before starting to write. Must satisfy `0 <= offset <= buf.length - 1`."
}
]
}
],
"desc": "Writes value
to buf
at the specified offset
. value
must be a valid\nsigned 8-bit integer. Behavior is undefined when value
is anything other than\na signed 8-bit integer.
value
is interpreted and written as a two's complement signed integer.
const buf = Buffer.allocUnsafe(2);\n\nbuf.writeInt8(2, 0);\nbuf.writeInt8(-2, 1);\n\nconsole.log(buf);\n// Prints: <Buffer 02 fe>\n
"
},
{
"textRaw": "`buf.writeInt16BE(value[, offset])`",
"type": "method",
"name": "writeInt16BE",
"meta": {
"added": [
"v0.5.5"
],
"changes": [
{
"version": "v10.0.0",
"pr-url": "https://github.com/nodejs/node/pull/18395",
"description": "Removed `noAssert` and no implicit coercion of the offset to `uint32` anymore."
}
]
},
"signatures": [
{
"return": {
"textRaw": "Returns: {integer} `offset` plus the number of bytes written.",
"name": "return",
"type": "integer",
"desc": "`offset` plus the number of bytes written."
},
"params": [
{
"textRaw": "`value` {integer} Number to be written to `buf`.",
"name": "value",
"type": "integer",
"desc": "Number to be written to `buf`."
},
{
"textRaw": "`offset` {integer} Number of bytes to skip before starting to write. Must satisfy `0 <= offset <= buf.length - 2`. **Default:** `0`.",
"name": "offset",
"type": "integer",
"default": "`0`",
"desc": "Number of bytes to skip before starting to write. Must satisfy `0 <= offset <= buf.length - 2`."
}
]
}
],
"desc": "Writes value
to buf
at the specified offset
as big-endian. The value
\nmust be a valid signed 16-bit integer. Behavior is undefined when value
is\nanything other than a signed 16-bit integer.
The value
is interpreted and written as a two's complement signed integer.
const buf = Buffer.allocUnsafe(2);\n\nbuf.writeInt16BE(0x0102, 0);\n\nconsole.log(buf);\n// Prints: <Buffer 01 02>\n
"
},
{
"textRaw": "`buf.writeInt16LE(value[, offset])`",
"type": "method",
"name": "writeInt16LE",
"meta": {
"added": [
"v0.5.5"
],
"changes": [
{
"version": "v10.0.0",
"pr-url": "https://github.com/nodejs/node/pull/18395",
"description": "Removed `noAssert` and no implicit coercion of the offset to `uint32` anymore."
}
]
},
"signatures": [
{
"return": {
"textRaw": "Returns: {integer} `offset` plus the number of bytes written.",
"name": "return",
"type": "integer",
"desc": "`offset` plus the number of bytes written."
},
"params": [
{
"textRaw": "`value` {integer} Number to be written to `buf`.",
"name": "value",
"type": "integer",
"desc": "Number to be written to `buf`."
},
{
"textRaw": "`offset` {integer} Number of bytes to skip before starting to write. Must satisfy `0 <= offset <= buf.length - 2`. **Default:** `0`.",
"name": "offset",
"type": "integer",
"default": "`0`",
"desc": "Number of bytes to skip before starting to write. Must satisfy `0 <= offset <= buf.length - 2`."
}
]
}
],
"desc": "Writes value
to buf
at the specified offset
as little-endian. The value
\nmust be a valid signed 16-bit integer. Behavior is undefined when value
is\nanything other than a signed 16-bit integer.
The value
is interpreted and written as a two's complement signed integer.
const buf = Buffer.allocUnsafe(2);\n\nbuf.writeInt16LE(0x0304, 0);\n\nconsole.log(buf);\n// Prints: <Buffer 04 03>\n
"
},
{
"textRaw": "`buf.writeInt32BE(value[, offset])`",
"type": "method",
"name": "writeInt32BE",
"meta": {
"added": [
"v0.5.5"
],
"changes": [
{
"version": "v10.0.0",
"pr-url": "https://github.com/nodejs/node/pull/18395",
"description": "Removed `noAssert` and no implicit coercion of the offset to `uint32` anymore."
}
]
},
"signatures": [
{
"return": {
"textRaw": "Returns: {integer} `offset` plus the number of bytes written.",
"name": "return",
"type": "integer",
"desc": "`offset` plus the number of bytes written."
},
"params": [
{
"textRaw": "`value` {integer} Number to be written to `buf`.",
"name": "value",
"type": "integer",
"desc": "Number to be written to `buf`."
},
{
"textRaw": "`offset` {integer} Number of bytes to skip before starting to write. Must satisfy `0 <= offset <= buf.length - 4`. **Default:** `0`.",
"name": "offset",
"type": "integer",
"default": "`0`",
"desc": "Number of bytes to skip before starting to write. Must satisfy `0 <= offset <= buf.length - 4`."
}
]
}
],
"desc": "Writes value
to buf
at the specified offset
as big-endian. The value
\nmust be a valid signed 32-bit integer. Behavior is undefined when value
is\nanything other than a signed 32-bit integer.
The value
is interpreted and written as a two's complement signed integer.
const buf = Buffer.allocUnsafe(4);\n\nbuf.writeInt32BE(0x01020304, 0);\n\nconsole.log(buf);\n// Prints: <Buffer 01 02 03 04>\n
"
},
{
"textRaw": "`buf.writeInt32LE(value[, offset])`",
"type": "method",
"name": "writeInt32LE",
"meta": {
"added": [
"v0.5.5"
],
"changes": [
{
"version": "v10.0.0",
"pr-url": "https://github.com/nodejs/node/pull/18395",
"description": "Removed `noAssert` and no implicit coercion of the offset to `uint32` anymore."
}
]
},
"signatures": [
{
"return": {
"textRaw": "Returns: {integer} `offset` plus the number of bytes written.",
"name": "return",
"type": "integer",
"desc": "`offset` plus the number of bytes written."
},
"params": [
{
"textRaw": "`value` {integer} Number to be written to `buf`.",
"name": "value",
"type": "integer",
"desc": "Number to be written to `buf`."
},
{
"textRaw": "`offset` {integer} Number of bytes to skip before starting to write. Must satisfy `0 <= offset <= buf.length - 4`. **Default:** `0`.",
"name": "offset",
"type": "integer",
"default": "`0`",
"desc": "Number of bytes to skip before starting to write. Must satisfy `0 <= offset <= buf.length - 4`."
}
]
}
],
"desc": "Writes value
to buf
at the specified offset
as little-endian. The value
\nmust be a valid signed 32-bit integer. Behavior is undefined when value
is\nanything other than a signed 32-bit integer.
The value
is interpreted and written as a two's complement signed integer.
const buf = Buffer.allocUnsafe(4);\n\nbuf.writeInt32LE(0x05060708, 0);\n\nconsole.log(buf);\n// Prints: <Buffer 08 07 06 05>\n
"
},
{
"textRaw": "`buf.writeIntBE(value, offset, byteLength)`",
"type": "method",
"name": "writeIntBE",
"meta": {
"added": [
"v0.11.15"
],
"changes": [
{
"version": "v10.0.0",
"pr-url": "https://github.com/nodejs/node/pull/18395",
"description": "Removed `noAssert` and no implicit coercion of the offset and `byteLength` to `uint32` anymore."
}
]
},
"signatures": [
{
"return": {
"textRaw": "Returns: {integer} `offset` plus the number of bytes written.",
"name": "return",
"type": "integer",
"desc": "`offset` plus the number of bytes written."
},
"params": [
{
"textRaw": "`value` {integer} Number to be written to `buf`.",
"name": "value",
"type": "integer",
"desc": "Number to be written to `buf`."
},
{
"textRaw": "`offset` {integer} Number of bytes to skip before starting to write. Must satisfy `0 <= offset <= buf.length - byteLength`.",
"name": "offset",
"type": "integer",
"desc": "Number of bytes to skip before starting to write. Must satisfy `0 <= offset <= buf.length - byteLength`."
},
{
"textRaw": "`byteLength` {integer} Number of bytes to write. Must satisfy `0 < byteLength <= 6`.",
"name": "byteLength",
"type": "integer",
"desc": "Number of bytes to write. Must satisfy `0 < byteLength <= 6`."
}
]
}
],
"desc": "Writes byteLength
bytes of value
to buf
at the specified offset
\nas big-endian. Supports up to 48 bits of accuracy. Behavior is undefined when\nvalue
is anything other than a signed integer.
const buf = Buffer.allocUnsafe(6);\n\nbuf.writeIntBE(0x1234567890ab, 0, 6);\n\nconsole.log(buf);\n// Prints: <Buffer 12 34 56 78 90 ab>\n
"
},
{
"textRaw": "`buf.writeIntLE(value, offset, byteLength)`",
"type": "method",
"name": "writeIntLE",
"meta": {
"added": [
"v0.11.15"
],
"changes": [
{
"version": "v10.0.0",
"pr-url": "https://github.com/nodejs/node/pull/18395",
"description": "Removed `noAssert` and no implicit coercion of the offset and `byteLength` to `uint32` anymore."
}
]
},
"signatures": [
{
"return": {
"textRaw": "Returns: {integer} `offset` plus the number of bytes written.",
"name": "return",
"type": "integer",
"desc": "`offset` plus the number of bytes written."
},
"params": [
{
"textRaw": "`value` {integer} Number to be written to `buf`.",
"name": "value",
"type": "integer",
"desc": "Number to be written to `buf`."
},
{
"textRaw": "`offset` {integer} Number of bytes to skip before starting to write. Must satisfy `0 <= offset <= buf.length - byteLength`.",
"name": "offset",
"type": "integer",
"desc": "Number of bytes to skip before starting to write. Must satisfy `0 <= offset <= buf.length - byteLength`."
},
{
"textRaw": "`byteLength` {integer} Number of bytes to write. Must satisfy `0 < byteLength <= 6`.",
"name": "byteLength",
"type": "integer",
"desc": "Number of bytes to write. Must satisfy `0 < byteLength <= 6`."
}
]
}
],
"desc": "Writes byteLength
bytes of value
to buf
at the specified offset
\nas little-endian. Supports up to 48 bits of accuracy. Behavior is undefined\nwhen value
is anything other than a signed integer.
const buf = Buffer.allocUnsafe(6);\n\nbuf.writeIntLE(0x1234567890ab, 0, 6);\n\nconsole.log(buf);\n// Prints: <Buffer ab 90 78 56 34 12>\n
"
},
{
"textRaw": "`buf.writeUInt8(value[, offset])`",
"type": "method",
"name": "writeUInt8",
"meta": {
"added": [
"v0.5.0"
],
"changes": [
{
"version": "v10.0.0",
"pr-url": "https://github.com/nodejs/node/pull/18395",
"description": "Removed `noAssert` and no implicit coercion of the offset to `uint32` anymore."
}
]
},
"signatures": [
{
"return": {
"textRaw": "Returns: {integer} `offset` plus the number of bytes written.",
"name": "return",
"type": "integer",
"desc": "`offset` plus the number of bytes written."
},
"params": [
{
"textRaw": "`value` {integer} Number to be written to `buf`.",
"name": "value",
"type": "integer",
"desc": "Number to be written to `buf`."
},
{
"textRaw": "`offset` {integer} Number of bytes to skip before starting to write. Must satisfy `0 <= offset <= buf.length - 1`. **Default:** `0`.",
"name": "offset",
"type": "integer",
"default": "`0`",
"desc": "Number of bytes to skip before starting to write. Must satisfy `0 <= offset <= buf.length - 1`."
}
]
}
],
"desc": "Writes value
to buf
at the specified offset
. value
must be a\nvalid unsigned 8-bit integer. Behavior is undefined when value
is anything\nother than an unsigned 8-bit integer.
const buf = Buffer.allocUnsafe(4);\n\nbuf.writeUInt8(0x3, 0);\nbuf.writeUInt8(0x4, 1);\nbuf.writeUInt8(0x23, 2);\nbuf.writeUInt8(0x42, 3);\n\nconsole.log(buf);\n// Prints: <Buffer 03 04 23 42>\n
"
},
{
"textRaw": "`buf.writeUInt16BE(value[, offset])`",
"type": "method",
"name": "writeUInt16BE",
"meta": {
"added": [
"v0.5.5"
],
"changes": [
{
"version": "v10.0.0",
"pr-url": "https://github.com/nodejs/node/pull/18395",
"description": "Removed `noAssert` and no implicit coercion of the offset to `uint32` anymore."
}
]
},
"signatures": [
{
"return": {
"textRaw": "Returns: {integer} `offset` plus the number of bytes written.",
"name": "return",
"type": "integer",
"desc": "`offset` plus the number of bytes written."
},
"params": [
{
"textRaw": "`value` {integer} Number to be written to `buf`.",
"name": "value",
"type": "integer",
"desc": "Number to be written to `buf`."
},
{
"textRaw": "`offset` {integer} Number of bytes to skip before starting to write. Must satisfy `0 <= offset <= buf.length - 2`. **Default:** `0`.",
"name": "offset",
"type": "integer",
"default": "`0`",
"desc": "Number of bytes to skip before starting to write. Must satisfy `0 <= offset <= buf.length - 2`."
}
]
}
],
"desc": "Writes value
to buf
at the specified offset
as big-endian. The value
\nmust be a valid unsigned 16-bit integer. Behavior is undefined when value
\nis anything other than an unsigned 16-bit integer.
const buf = Buffer.allocUnsafe(4);\n\nbuf.writeUInt16BE(0xdead, 0);\nbuf.writeUInt16BE(0xbeef, 2);\n\nconsole.log(buf);\n// Prints: <Buffer de ad be ef>\n
"
},
{
"textRaw": "`buf.writeUInt16LE(value[, offset])`",
"type": "method",
"name": "writeUInt16LE",
"meta": {
"added": [
"v0.5.5"
],
"changes": [
{
"version": "v10.0.0",
"pr-url": "https://github.com/nodejs/node/pull/18395",
"description": "Removed `noAssert` and no implicit coercion of the offset to `uint32` anymore."
}
]
},
"signatures": [
{
"return": {
"textRaw": "Returns: {integer} `offset` plus the number of bytes written.",
"name": "return",
"type": "integer",
"desc": "`offset` plus the number of bytes written."
},
"params": [
{
"textRaw": "`value` {integer} Number to be written to `buf`.",
"name": "value",
"type": "integer",
"desc": "Number to be written to `buf`."
},
{
"textRaw": "`offset` {integer} Number of bytes to skip before starting to write. Must satisfy `0 <= offset <= buf.length - 2`. **Default:** `0`.",
"name": "offset",
"type": "integer",
"default": "`0`",
"desc": "Number of bytes to skip before starting to write. Must satisfy `0 <= offset <= buf.length - 2`."
}
]
}
],
"desc": "Writes value
to buf
at the specified offset
as little-endian. The value
\nmust be a valid unsigned 16-bit integer. Behavior is undefined when value
is\nanything other than an unsigned 16-bit integer.
const buf = Buffer.allocUnsafe(4);\n\nbuf.writeUInt16LE(0xdead, 0);\nbuf.writeUInt16LE(0xbeef, 2);\n\nconsole.log(buf);\n// Prints: <Buffer ad de ef be>\n
"
},
{
"textRaw": "`buf.writeUInt32BE(value[, offset])`",
"type": "method",
"name": "writeUInt32BE",
"meta": {
"added": [
"v0.5.5"
],
"changes": [
{
"version": "v10.0.0",
"pr-url": "https://github.com/nodejs/node/pull/18395",
"description": "Removed `noAssert` and no implicit coercion of the offset to `uint32` anymore."
}
]
},
"signatures": [
{
"return": {
"textRaw": "Returns: {integer} `offset` plus the number of bytes written.",
"name": "return",
"type": "integer",
"desc": "`offset` plus the number of bytes written."
},
"params": [
{
"textRaw": "`value` {integer} Number to be written to `buf`.",
"name": "value",
"type": "integer",
"desc": "Number to be written to `buf`."
},
{
"textRaw": "`offset` {integer} Number of bytes to skip before starting to write. Must satisfy `0 <= offset <= buf.length - 4`. **Default:** `0`.",
"name": "offset",
"type": "integer",
"default": "`0`",
"desc": "Number of bytes to skip before starting to write. Must satisfy `0 <= offset <= buf.length - 4`."
}
]
}
],
"desc": "Writes value
to buf
at the specified offset
as big-endian. The value
\nmust be a valid unsigned 32-bit integer. Behavior is undefined when value
\nis anything other than an unsigned 32-bit integer.
const buf = Buffer.allocUnsafe(4);\n\nbuf.writeUInt32BE(0xfeedface, 0);\n\nconsole.log(buf);\n// Prints: <Buffer fe ed fa ce>\n
"
},
{
"textRaw": "`buf.writeUInt32LE(value[, offset])`",
"type": "method",
"name": "writeUInt32LE",
"meta": {
"added": [
"v0.5.5"
],
"changes": [
{
"version": "v10.0.0",
"pr-url": "https://github.com/nodejs/node/pull/18395",
"description": "Removed `noAssert` and no implicit coercion of the offset to `uint32` anymore."
}
]
},
"signatures": [
{
"return": {
"textRaw": "Returns: {integer} `offset` plus the number of bytes written.",
"name": "return",
"type": "integer",
"desc": "`offset` plus the number of bytes written."
},
"params": [
{
"textRaw": "`value` {integer} Number to be written to `buf`.",
"name": "value",
"type": "integer",
"desc": "Number to be written to `buf`."
},
{
"textRaw": "`offset` {integer} Number of bytes to skip before starting to write. Must satisfy `0 <= offset <= buf.length - 4`. **Default:** `0`.",
"name": "offset",
"type": "integer",
"default": "`0`",
"desc": "Number of bytes to skip before starting to write. Must satisfy `0 <= offset <= buf.length - 4`."
}
]
}
],
"desc": "Writes value
to buf
at the specified offset
as little-endian. The value
\nmust be a valid unsigned 32-bit integer. Behavior is undefined when value
is\nanything other than an unsigned 32-bit integer.
const buf = Buffer.allocUnsafe(4);\n\nbuf.writeUInt32LE(0xfeedface, 0);\n\nconsole.log(buf);\n// Prints: <Buffer ce fa ed fe>\n
"
},
{
"textRaw": "`buf.writeUIntBE(value, offset, byteLength)`",
"type": "method",
"name": "writeUIntBE",
"meta": {
"added": [
"v0.5.5"
],
"changes": [
{
"version": "v10.0.0",
"pr-url": "https://github.com/nodejs/node/pull/18395",
"description": "Removed `noAssert` and no implicit coercion of the offset and `byteLength` to `uint32` anymore."
}
]
},
"signatures": [
{
"return": {
"textRaw": "Returns: {integer} `offset` plus the number of bytes written.",
"name": "return",
"type": "integer",
"desc": "`offset` plus the number of bytes written."
},
"params": [
{
"textRaw": "`value` {integer} Number to be written to `buf`.",
"name": "value",
"type": "integer",
"desc": "Number to be written to `buf`."
},
{
"textRaw": "`offset` {integer} Number of bytes to skip before starting to write. Must satisfy `0 <= offset <= buf.length - byteLength`.",
"name": "offset",
"type": "integer",
"desc": "Number of bytes to skip before starting to write. Must satisfy `0 <= offset <= buf.length - byteLength`."
},
{
"textRaw": "`byteLength` {integer} Number of bytes to write. Must satisfy `0 < byteLength <= 6`.",
"name": "byteLength",
"type": "integer",
"desc": "Number of bytes to write. Must satisfy `0 < byteLength <= 6`."
}
]
}
],
"desc": "Writes byteLength
bytes of value
to buf
at the specified offset
\nas big-endian. Supports up to 48 bits of accuracy. Behavior is undefined\nwhen value
is anything other than an unsigned integer.
const buf = Buffer.allocUnsafe(6);\n\nbuf.writeUIntBE(0x1234567890ab, 0, 6);\n\nconsole.log(buf);\n// Prints: <Buffer 12 34 56 78 90 ab>\n
"
},
{
"textRaw": "`buf.writeUIntLE(value, offset, byteLength)`",
"type": "method",
"name": "writeUIntLE",
"meta": {
"added": [
"v0.5.5"
],
"changes": [
{
"version": "v10.0.0",
"pr-url": "https://github.com/nodejs/node/pull/18395",
"description": "Removed `noAssert` and no implicit coercion of the offset and `byteLength` to `uint32` anymore."
}
]
},
"signatures": [
{
"return": {
"textRaw": "Returns: {integer} `offset` plus the number of bytes written.",
"name": "return",
"type": "integer",
"desc": "`offset` plus the number of bytes written."
},
"params": [
{
"textRaw": "`value` {integer} Number to be written to `buf`.",
"name": "value",
"type": "integer",
"desc": "Number to be written to `buf`."
},
{
"textRaw": "`offset` {integer} Number of bytes to skip before starting to write. Must satisfy `0 <= offset <= buf.length - byteLength`.",
"name": "offset",
"type": "integer",
"desc": "Number of bytes to skip before starting to write. Must satisfy `0 <= offset <= buf.length - byteLength`."
},
{
"textRaw": "`byteLength` {integer} Number of bytes to write. Must satisfy `0 < byteLength <= 6`.",
"name": "byteLength",
"type": "integer",
"desc": "Number of bytes to write. Must satisfy `0 < byteLength <= 6`."
}
]
}
],
"desc": "Writes byteLength
bytes of value
to buf
at the specified offset
\nas little-endian. Supports up to 48 bits of accuracy. Behavior is undefined\nwhen value
is anything other than an unsigned integer.
const buf = Buffer.allocUnsafe(6);\n\nbuf.writeUIntLE(0x1234567890ab, 0, 6);\n\nconsole.log(buf);\n// Prints: <Buffer ab 90 78 56 34 12>\n
"
}
],
"signatures": [
{
"params": [
{
"textRaw": "`array` {integer[]} An array of bytes to copy from.",
"name": "array",
"type": "integer[]",
"desc": "An array of bytes to copy from."
}
],
"desc": "See Buffer.from(array)
.
See\nBuffer.from(arrayBuffer[, byteOffset[, length]])
.
See Buffer.from(buffer)
.
See Buffer.alloc()
and Buffer.allocUnsafe()
. This variant of the\nconstructor is equivalent to Buffer.alloc()
.