\n\nStability: 2 - Stable
\n
Prior to the introduction of TypedArray in ECMAScript 2015 (ES6), the\nJavaScript language had no mechanism for reading or manipulating streams\nof binary data. The Buffer class was introduced as part of the Node.js\nAPI to make it possible to interact with octet streams in the context of things\nlike TCP streams and file system operations.
Now that TypedArray has been added in ES6, the Buffer class implements the\nUint8Array API in a manner that is more optimized and suitable for Node.js'\nuse cases.
Instances of the Buffer class are similar to arrays of integers but\ncorrespond to fixed-sized, raw memory allocations outside the V8 heap.\nThe size of the Buffer is established when it is created and cannot be\nchanged.
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, filled with 0x1.\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 either fill() or write().\nconst buf3 = Buffer.allocUnsafe(10);\n\n// Creates a Buffer containing [0x1, 0x2, 0x3].\nconst buf4 = Buffer.from([1, 2, 3]);\n\n// Creates a Buffer containing UTF-8 bytes [0x74, 0xc3, 0xa9, 0x73, 0x74].\nconst buf5 = Buffer.from('tést');\n\n// Creates a Buffer containing Latin-1 bytes [0x74, 0xe9, 0x73, 0x74].\nconst buf6 = Buffer.from('tést', 'latin1');\nIn 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. While 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. Starting in Node.js 8.0.0, Buffer(num) and\nnew Buffer(num) will 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 that\nshares 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.
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.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() may be allocated off\na shared internal memory pool if size is less than or equal to half\nBuffer.poolSize. Instances returned by Buffer.allocUnsafeSlow() never\nuse the shared internal memory pool.
Node.js can be started using the --zero-fill-buffers command line option to\nforce all newly allocated Buffer instances created using either\nnew Buffer(size), Buffer.allocUnsafe(), Buffer.allocUnsafeSlow() or\nnew SlowBuffer(size) to be automatically zero-filled upon creation. Use of\nthis flag changes the default behavior of these methods and can have a significant\nimpact on performance. Use of the --zero-fill-buffers option is recommended\nonly when necessary to enforce that newly allocated Buffer instances cannot\ncontain old data that is potentially sensitive.
$ node --zero-fill-buffers\n> Buffer.allocUnsafe(5);\n<Buffer 00 00 00 00 00>\nWhen 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 memory\ncan allow this old data to be leaked when the Buffer memory is read.
While there are clear performance advantages to using Buffer.allocUnsafe(),\nextra care must be taken in order to avoid introducing security\nvulnerabilities into an application.
Buffer instances are commonly used to represent sequences of encoded characters\nsuch as UTF-8, UCS2, Base64, or even Hex-encoded data. It is possible to\nconvert back and forth between Buffer instances and ordinary JavaScript strings\nby using an explicit character encoding.
const buf = Buffer.from('hello world', 'ascii');\n\nconsole.log(buf.toString('hex'));\n// Prints: 68656c6c6f20776f726c64\nconsole.log(buf.toString('base64'));\n// Prints: aGVsbG8gd29ybGQ=\nThe character encodings currently supported by Node.js include:
\n'ascii' - For 7-bit ASCII data only. This encoding is fast and will strip\nthe high bit if set.
'utf8' - Multibyte encoded Unicode characters. Many web pages and other\ndocument formats use UTF-8.
'utf16le' - 2 or 4 bytes, little-endian encoded Unicode characters.\nSurrogate pairs (U+10000 to U+10FFFF) are supported.
'ucs2' - Alias of 'utf16le'.
'base64' - Base64 encoding. When creating a Buffer from a string,\nthis encoding will also correctly accept "URL and Filename Safe Alphabet" as\nspecified in RFC4648, Section 5.
'latin1' - A way of encoding the Buffer into a one-byte encoded string\n(as defined by the IANA in RFC1345,\npage 63, to be the Latin-1 supplement block and C0/C1 control codes).
'binary' - Alias for 'latin1'.
'hex' - Encode each byte as two hexadecimal characters.
Modern 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\nwin-1252-encoded data, and using 'latin1' encoding may incorrectly decode the\ncharacters.
Buffer instances are also Uint8Array instances. However, there are subtle\nincompatibilities with the TypedArray specification in ECMAScript 2015.\nFor example, while ArrayBuffer#slice() creates a copy of the slice, the\nimplementation of Buffer#slice() creates a view over the\nexisting Buffer without copying, making Buffer#slice() far\nmore efficient.
It is also possible to create new TypedArray instances from a Buffer with\nthe following caveats:
The Buffer object's memory is copied to the TypedArray, not shared.
The Buffer object's memory is interpreted as an array of distinct\nelements, and not as a byte array of the target type. That is,\nnew Uint32Array(Buffer.from([1, 2, 3, 4])) creates a 4-element Uint32Array\nwith elements [1, 2, 3, 4], not a Uint32Array with a single element\n[0x1020304] or [0x4030201].
It is possible to create a new Buffer that shares the same allocated memory as\na TypedArray instance by using the TypeArray object's .buffer property.
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// 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>\nNote that when 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\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 the ECMAScript 2015 (ES6) for..of\nsyntax.
const buf = Buffer.from([1, 2, 3]);\n\n// Prints:\n// 1\n// 2\n// 3\nfor (const b of buf) {\n console.log(b);\n}\nAdditionally, the buf.values(), buf.keys(), and\nbuf.entries() methods can be used to create iterators.
Note that buffer.constants is a property on the buffer module returned by\nrequire('buffer'), not on the Buffer global or a Buffer instance.
Buffer instance.On 32-bit architectures, this value is (2^30)-1 (~1GB).\nOn 64-bit architectures, this value is (2^31)-1 (~2GB).
This value is also available as buffer.kMaxLength.
string instance.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.
\n", "type": "module", "displayName": "buffer.constants.MAX_STRING_LENGTH" } ], "type": "module", "displayName": "Buffer Constants" } ], "classes": [ { "textRaw": "Class: Buffer", "type": "class", "name": "Buffer", "desc": "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>\nAllocates a new Buffer of size bytes. If the size is larger than\nbuffer.constants.MAX_LENGTH or smaller than 0, a RangeError will be\nthrown. A zero-length Buffer will be created if size is 0.
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>\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>\nCalling Buffer.alloc() can be significantly slower than the alternative\nBuffer.allocUnsafe() but ensures that the newly created Buffer instance\ncontents will never contain sensitive data.
A TypeError will be thrown if size is not a number.
Allocates a new Buffer of size bytes. If the size is larger than\nbuffer.constants.MAX_LENGTH or smaller than 0, a RangeError will be\nthrown. A zero-length Buffer will be 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 Buffer.alloc() instead to initialize\nBuffer instances to 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>\nA TypeError will be thrown if size is not a number.
Note that 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() and the deprecated\nnew Buffer(size) constructor only when size is less than or equal to\nBuffer.poolSize >> 1 (floor of Buffer.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 the size is larger than\nbuffer.constants.MAX_LENGTH or smaller than 0, a RangeError will be\nthrown. A zero-length Buffer will be 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 such\nBuffer instances to zeroes.
When using Buffer.allocUnsafe() to allocate new Buffer instances,\nallocations under 4KB are, by default, sliced from a single pre-allocated\nBuffer. This allows applications to avoid the garbage collection overhead of\ncreating many individually allocated Buffer instances. This approach improves\nboth performance and memory usage by eliminating the need to track and cleanup as\nmany Persistent 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() then\ncopy out the relevant bits.
// Need to keep around a few small chunks of memory\nconst store = [];\n\nsocket.on('readable', () => {\n const data = socket.read();\n\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});\nUse of Buffer.allocUnsafeSlow() should be used only as a last resort after\na developer has observed undue memory retention in their applications.
A TypeError will be thrown if size is not a number.
Returns the actual byte length of a string. This is not the same as\nString.prototype.length since that returns the number of characters in\na string.
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\nWhen string is a Buffer/DataView/TypedArray/ArrayBuffer/\nSharedArrayBuffer, the actual byte length is 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])\nReturns 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. This however causes an additional loop to be executed in order to\ncalculate the totalLength, so it is faster to provide the length explicitly if\nit is already known.
If totalLength is provided, it is coerced to an unsigned integer. If the\ncombined length of the Buffers 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\nAllocates a new Buffer using an array of octets.
// Creates a new Buffer containing UTF-8 bytes of the string 'buffer'\nconst buf = Buffer.from([0x62, 0x75, 0x66, 0x66, 0x65, 0x72]);\nA TypeError will be thrown if array is not an Array.
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>\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\nA TypeError will be thrown if arrayBuffer is not an ArrayBuffer or a\nSharedArrayBuffer.
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\nA TypeError will be thrown if buffer is not a Buffer.
Creates a new Buffer containing the given JavaScript string string. If\nprovided, the encoding parameter identifies the character encoding of string.
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('ascii'));\n// Prints: this is a tC)st\nA TypeError will be thrown if string is not a string.
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>\nFor objects that support Symbol.toPrimitive, returns\nBuffer.from(object[Symbol.toPrimitive](), offsetOrEncoding, length).
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>\nReturns true if obj is a Buffer, false otherwise.
Returns true if encoding contains a supported character encoding, or false\notherwise.
This is the number of bytes used to determine the size of pre-allocated, internal\nBuffer instances used for 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 - that is, getting returns undefined and\nsetting does nothing.
// Copy an ASCII string into a `Buffer` one byte at a time.\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('ascii'));\n// Prints: Node.js\nThe buffer property references the underlying ArrayBuffer object based on\nwhich this Buffer object is created.
const arrayBuffer = new ArrayBuffer(16);\nconst buffer = Buffer.from(arrayBuffer);\n\nconsole.log(buffer.buffer === arrayBuffer);\n// Prints: true\nReturns the amount of memory allocated for buf in bytes. Note that this\ndoes not necessarily reflect the amount of "usable" data within buf.
// Create a `Buffer` and write a shorter ASCII string to it.\n\nconst buf = Buffer.alloc(1234);\n\nconsole.log(buf.length);\n// Prints: 1234\n\nbuf.write('some string', 0, 'ascii');\n\nconsole.log(buf.length);\n// Prints: 1234\nWhile the length property is not immutable, changing the value of length\ncan result in undefined and inconsistent behavior. Applications that wish to\nmodify the length of a Buffer should therefore treat length as read-only and\nuse buf.slice() to create a new Buffer.
let buf = Buffer.allocUnsafe(10);\n\nbuf.write('abcdefghj', 0, 'ascii');\n\nconsole.log(buf.length);\n// Prints: 10\n\nbuf = buf.slice(0, 5);\n\nconsole.log(buf.length);\n// Prints: 5\nThe 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 buf1 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])\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\nA RangeError will be 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.
// 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\nconsole.log(buf2.toString('ascii', 0, 25));\n// Prints: !!!!!!!!qrst!!!!!!!!!!!!!\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\nCreates and returns an iterator of [index, byte] pairs from the contents of\nbuf.
// 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]\nReturns true if both buf and otherBuffer have exactly the same bytes,\nfalse otherwise.
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\nFills buf with the specified value. If the offset and end are not given,\nthe entire buf will be filled. This is meant to be a small simplification to\nallow the creation and filling of a Buffer to be done on a single line.
// Fill a `Buffer` with the ASCII character 'h'.\n\nconst b = Buffer.allocUnsafe(50).fill('h');\n\nconsole.log(b.toString());\n// Prints: hhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhh\nvalue is coerced to a uint32 value if it is not a String or Integer.
If the final write of a fill() operation falls on a multi-byte character,\nthen only the first bytes of that character that fit into buf are written.
// Fill a `Buffer` with a two-byte character.\n\nconsole.log(Buffer.allocUnsafe(3).fill('\\u0222'));\n// Prints: <Buffer c8 a2 c8>\nIf value contains invalid characters, it is truncated; if no valid\nfill data remains, no filling is performed:
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.\nEquivalent 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\nIf 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', 'ucs2');\n\nconsole.log(utf16Buffer.indexOf('\\u03a3', 0, 'ucs2'));\n// Prints: 4\nconsole.log(utf16Buffer.indexOf('\\u03a3', -4, 'ucs2'));\n// Prints: 6\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 or 0, like {}, [], null or undefined, will search\nthe whole buffer. This behavior 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', []));\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\nIdentical to buf.indexOf(), except buf is searched from back to front\ninstead of front to back.
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', 'ucs2');\n\nconsole.log(utf16Buffer.lastIndexOf('\\u03a3', undefined, 'ucs2'));\n// Prints: 6\nconsole.log(utf16Buffer.lastIndexOf('\\u03a3', -5, 'ucs2'));\n// Prints: 4\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', []));\nIf value is an empty string or empty Buffer, byteOffset will be returned.
Reads a 64-bit double from buf at the specified offset with specified\nendian format (readDoubleBE() returns big endian, readDoubleLE() returns\nlittle endian).
Setting noAssert to true allows offset to be beyond the end of buf, but\nthe resulting behavior is undefined.
const buf = Buffer.from([1, 2, 3, 4, 5, 6, 7, 8]);\n\nconsole.log(buf.readDoubleBE());\n// Prints: 8.20788039913184e-304\nconsole.log(buf.readDoubleLE());\n// Prints: 5.447603722011605e-270\nconsole.log(buf.readDoubleLE(1));\n// Throws an exception: RangeError: Index out of range\nconsole.log(buf.readDoubleLE(1, true));\n// Warning: reads passed end of buffer!\n// This will result in a segmentation fault! Don't do this!\nReads a 64-bit double from buf at the specified offset with specified\nendian format (readDoubleBE() returns big endian, readDoubleLE() returns\nlittle endian).
Setting noAssert to true allows offset to be beyond the end of buf, but\nthe resulting behavior is undefined.
const buf = Buffer.from([1, 2, 3, 4, 5, 6, 7, 8]);\n\nconsole.log(buf.readDoubleBE());\n// Prints: 8.20788039913184e-304\nconsole.log(buf.readDoubleLE());\n// Prints: 5.447603722011605e-270\nconsole.log(buf.readDoubleLE(1));\n// Throws an exception: RangeError: Index out of range\nconsole.log(buf.readDoubleLE(1, true));\n// Warning: reads passed end of buffer!\n// This will result in a segmentation fault! Don't do this!\nReads a 32-bit float from buf at the specified offset with specified\nendian format (readFloatBE() returns big endian, readFloatLE() returns\nlittle endian).
Setting noAssert to true allows offset to be beyond the end of buf, but\nthe resulting behavior is undefined.
const buf = Buffer.from([1, 2, 3, 4]);\n\nconsole.log(buf.readFloatBE());\n// Prints: 2.387939260590663e-38\nconsole.log(buf.readFloatLE());\n// Prints: 1.539989614439558e-36\nconsole.log(buf.readFloatLE(1));\n// Throws an exception: RangeError: Index out of range\nconsole.log(buf.readFloatLE(1, true));\n// Warning: reads passed end of buffer!\n// This will result in a segmentation fault! Don't do this!\nReads a 32-bit float from buf at the specified offset with specified\nendian format (readFloatBE() returns big endian, readFloatLE() returns\nlittle endian).
Setting noAssert to true allows offset to be beyond the end of buf, but\nthe resulting behavior is undefined.
const buf = Buffer.from([1, 2, 3, 4]);\n\nconsole.log(buf.readFloatBE());\n// Prints: 2.387939260590663e-38\nconsole.log(buf.readFloatLE());\n// Prints: 1.539989614439558e-36\nconsole.log(buf.readFloatLE(1));\n// Throws an exception: RangeError: Index out of range\nconsole.log(buf.readFloatLE(1, true));\n// Warning: reads passed end of buffer!\n// This will result in a segmentation fault! Don't do this!\nReads a signed 8-bit integer from buf at the specified offset.
Setting noAssert to true allows offset to be beyond the end of buf, but\nthe resulting behavior is undefined.
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 an exception: RangeError: Index out of range\nReads a signed 16-bit integer from buf at the specified offset with\nthe specified endian format (readInt16BE() returns big endian,\nreadInt16LE() returns little endian).
Setting noAssert to true allows offset to be beyond the end of buf, but\nthe resulting behavior is undefined.
Integers read from a Buffer are interpreted as two's complement signed values.
const buf = Buffer.from([0, 5]);\n\nconsole.log(buf.readInt16BE());\n// Prints: 5\nconsole.log(buf.readInt16LE());\n// Prints: 1280\nconsole.log(buf.readInt16LE(1));\n// Throws an exception: RangeError: Index out of range\nReads a signed 16-bit integer from buf at the specified offset with\nthe specified endian format (readInt16BE() returns big endian,\nreadInt16LE() returns little endian).
Setting noAssert to true allows offset to be beyond the end of buf, but\nthe resulting behavior is undefined.
Integers read from a Buffer are interpreted as two's complement signed values.
const buf = Buffer.from([0, 5]);\n\nconsole.log(buf.readInt16BE());\n// Prints: 5\nconsole.log(buf.readInt16LE());\n// Prints: 1280\nconsole.log(buf.readInt16LE(1));\n// Throws an exception: RangeError: Index out of range\nReads a signed 32-bit integer from buf at the specified offset with\nthe specified endian format (readInt32BE() returns big endian,\nreadInt32LE() returns little endian).
Setting noAssert to true allows offset to be beyond the end of buf, but\nthe resulting behavior is undefined.
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());\n// Prints: 5\nconsole.log(buf.readInt32LE());\n// Prints: 83886080\nconsole.log(buf.readInt32LE(1));\n// Throws an exception: RangeError: Index out of range\nReads a signed 32-bit integer from buf at the specified offset with\nthe specified endian format (readInt32BE() returns big endian,\nreadInt32LE() returns little endian).
Setting noAssert to true allows offset to be beyond the end of buf, but\nthe resulting behavior is undefined.
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());\n// Prints: 5\nconsole.log(buf.readInt32LE());\n// Prints: 83886080\nconsole.log(buf.readInt32LE(1));\n// Throws an exception: RangeError: Index out of range\nReads byteLength number of bytes from buf at the specified offset\nand interprets the result as a two's complement signed value. Supports up to 48\nbits of accuracy.
Setting noAssert to true allows offset to be beyond the end of buf, but\nthe resulting behavior is undefined.
const buf = Buffer.from([0x12, 0x34, 0x56, 0x78, 0x90, 0xab]);\n\nconsole.log(buf.readIntLE(0, 6).toString(16));\n// Prints: -546f87a9cbee\nconsole.log(buf.readIntBE(0, 6).toString(16));\n// Prints: 1234567890ab\nconsole.log(buf.readIntBE(1, 6).toString(16));\n// Throws: RangeError [ERR_INDEX_OUT_OF_RANGE]: Index out of range\nReads byteLength number of bytes from buf at the specified offset\nand interprets the result as a two's complement signed value. Supports up to 48\nbits of accuracy.
Setting noAssert to true allows offset to be beyond the end of buf, but\nthe resulting behavior is undefined.
const buf = Buffer.from([0x12, 0x34, 0x56, 0x78, 0x90, 0xab]);\n\nconsole.log(buf.readIntLE(0, 6).toString(16));\n// Prints: -546f87a9cbee\nconsole.log(buf.readIntBE(0, 6).toString(16));\n// Prints: 1234567890ab\nconsole.log(buf.readIntBE(1, 6).toString(16));\n// Throws: RangeError [ERR_INDEX_OUT_OF_RANGE]: Index out of range\nReads an unsigned 8-bit integer from buf at the specified offset.
Setting noAssert to true allows offset to be beyond the end of buf, but\nthe resulting behavior is undefined.
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 an exception: RangeError: Index out of range\nReads an unsigned 16-bit integer from buf at the specified offset with\nspecified endian format (readUInt16BE() returns big endian, readUInt16LE()\nreturns little endian).
Setting noAssert to true allows offset to be beyond the end of buf, but\nthe resulting behavior is undefined.
const buf = Buffer.from([0x12, 0x34, 0x56]);\n\nconsole.log(buf.readUInt16BE(0).toString(16));\n// Prints: 1234\nconsole.log(buf.readUInt16LE(0).toString(16));\n// Prints: 3412\nconsole.log(buf.readUInt16BE(1).toString(16));\n// Prints: 3456\nconsole.log(buf.readUInt16LE(1).toString(16));\n// Prints: 5634\nconsole.log(buf.readUInt16LE(2).toString(16));\n// Throws an exception: RangeError: Index out of range\nReads an unsigned 16-bit integer from buf at the specified offset with\nspecified endian format (readUInt16BE() returns big endian, readUInt16LE()\nreturns little endian).
Setting noAssert to true allows offset to be beyond the end of buf, but\nthe resulting behavior is undefined.
const buf = Buffer.from([0x12, 0x34, 0x56]);\n\nconsole.log(buf.readUInt16BE(0).toString(16));\n// Prints: 1234\nconsole.log(buf.readUInt16LE(0).toString(16));\n// Prints: 3412\nconsole.log(buf.readUInt16BE(1).toString(16));\n// Prints: 3456\nconsole.log(buf.readUInt16LE(1).toString(16));\n// Prints: 5634\nconsole.log(buf.readUInt16LE(2).toString(16));\n// Throws an exception: RangeError: Index out of range\nReads an unsigned 32-bit integer from buf at the specified offset with\nspecified endian format (readUInt32BE() returns big endian,\nreadUInt32LE() returns little endian).
Setting noAssert to true allows offset to be beyond the end of buf, but\nthe resulting behavior is undefined.
const buf = Buffer.from([0x12, 0x34, 0x56, 0x78]);\n\nconsole.log(buf.readUInt32BE(0).toString(16));\n// Prints: 12345678\nconsole.log(buf.readUInt32LE(0).toString(16));\n// Prints: 78563412\nconsole.log(buf.readUInt32LE(1).toString(16));\n// Throws an exception: RangeError: Index out of range\nReads an unsigned 32-bit integer from buf at the specified offset with\nspecified endian format (readUInt32BE() returns big endian,\nreadUInt32LE() returns little endian).
Setting noAssert to true allows offset to be beyond the end of buf, but\nthe resulting behavior is undefined.
const buf = Buffer.from([0x12, 0x34, 0x56, 0x78]);\n\nconsole.log(buf.readUInt32BE(0).toString(16));\n// Prints: 12345678\nconsole.log(buf.readUInt32LE(0).toString(16));\n// Prints: 78563412\nconsole.log(buf.readUInt32LE(1).toString(16));\n// Throws an exception: RangeError: Index out of range\nReads byteLength number of bytes from buf at the specified offset\nand interprets the result as an unsigned integer. Supports up to 48\nbits of accuracy.
Setting noAssert to true allows offset to be beyond the end of buf, but\nthe resulting behavior is undefined.
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.readUIntLE(0, 6).toString(16));\n// Prints: ab9078563412\nconsole.log(buf.readUIntBE(1, 6).toString(16));\n// Throws an exception: RangeError: Index out of range\nReads byteLength number of bytes from buf at the specified offset\nand interprets the result as an unsigned integer. Supports up to 48\nbits of accuracy.
Setting noAssert to true allows offset to be beyond the end of buf, but\nthe resulting behavior is undefined.
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.readUIntLE(0, 6).toString(16));\n// Prints: ab9078563412\nconsole.log(buf.readUIntBE(1, 6).toString(16));\n// Throws an exception: RangeError: Index out of range\nReturns 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.
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.slice(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\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.slice(-6, -1).toString());\n// Prints: buffe\n// (Equivalent to buf.slice(0, 5))\n\nconsole.log(buf.slice(-6, -2).toString());\n// Prints: buff\n// (Equivalent to buf.slice(0, 4))\n\nconsole.log(buf.slice(-5, -2).toString());\n// Prints: uff\n// (Equivalent to buf.slice(1, 4))\nInterprets buf as an array of unsigned 16-bit integers and swaps the byte-order\nin-place. Throws a RangeError if buf.length is 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 an exception: RangeError: Buffer size must be a multiple of 16-bits\nInterprets buf as an array of unsigned 32-bit integers and swaps the byte-order\nin-place. Throws a RangeError if buf.length is 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 an exception: RangeError: Buffer size must be a multiple of 32-bits\nInterprets buf as an array of 64-bit numbers and swaps the byte-order in-place.\nThrows a RangeError 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 an exception: RangeError: Buffer size must be a multiple of 64-bits\nNote that JavaScript cannot encode 64-bit integers. This method is intended\nfor working with 64-bit floats.
\n" }, { "textRaw": "buf.toJSON()", "type": "method", "name": "toJSON", "meta": { "added": [ "v0.9.2" ], "changes": [] }, "signatures": [ { "return": { "textRaw": "Returns: {Object} ", "name": "return", "type": "Object" }, "params": [] }, { "params": [] } ], "desc": "Returns a JSON representation of buf. JSON.stringify() implicitly calls\nthis function when stringifying a Buffer instance.
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.data) :\n value;\n});\n\nconsole.log(copy);\n// Prints: <Buffer 01 02 03 04 05>\nDecodes 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.
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('ascii'));\n// Prints: abcdefghijklmnopqrstuvwxyz\nconsole.log(buf1.toString('ascii', 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\nCreates 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\nWrites string to buf at offset according to the character encoding in encoding.\nThe length parameter is the number of bytes to write. If buf did not contain\nenough space to fit the entire string, only a partial amount of string will\nbe written. However, partially encoded characters will not be written.
const buf = Buffer.allocUnsafe(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\nWrites value to buf at the specified offset with specified endian\nformat (writeDoubleBE() writes big endian, writeDoubleLE() writes little\nendian). value should be a valid 64-bit double. Behavior is undefined when\nvalue is anything other than a 64-bit double.
Setting noAssert to true allows the encoded form of value to extend beyond\nthe end of buf, but the resulting behavior is undefined.
const buf = Buffer.allocUnsafe(8);\n\nbuf.writeDoubleBE(0xdeadbeefcafebabe, 0);\n\nconsole.log(buf);\n// Prints: <Buffer 43 eb d5 b7 dd f9 5f d7>\n\nbuf.writeDoubleLE(0xdeadbeefcafebabe, 0);\n\nconsole.log(buf);\n// Prints: <Buffer d7 5f f9 dd b7 d5 eb 43>\nWrites value to buf at the specified offset with specified endian\nformat (writeDoubleBE() writes big endian, writeDoubleLE() writes little\nendian). value should be a valid 64-bit double. Behavior is undefined when\nvalue is anything other than a 64-bit double.
Setting noAssert to true allows the encoded form of value to extend beyond\nthe end of buf, but the resulting behavior is undefined.
const buf = Buffer.allocUnsafe(8);\n\nbuf.writeDoubleBE(0xdeadbeefcafebabe, 0);\n\nconsole.log(buf);\n// Prints: <Buffer 43 eb d5 b7 dd f9 5f d7>\n\nbuf.writeDoubleLE(0xdeadbeefcafebabe, 0);\n\nconsole.log(buf);\n// Prints: <Buffer d7 5f f9 dd b7 d5 eb 43>\nWrites value to buf at the specified offset with specified endian\nformat (writeFloatBE() writes big endian, writeFloatLE() writes little\nendian). value should be a valid 32-bit float. Behavior is undefined when\nvalue is anything other than a 32-bit float.
Setting noAssert to true allows the encoded form of value to extend beyond\nthe end of buf, but the resulting behavior is undefined.
const buf = Buffer.allocUnsafe(4);\n\nbuf.writeFloatBE(0xcafebabe, 0);\n\nconsole.log(buf);\n// Prints: <Buffer 4f 4a fe bb>\n\nbuf.writeFloatLE(0xcafebabe, 0);\n\nconsole.log(buf);\n// Prints: <Buffer bb fe 4a 4f>\nWrites value to buf at the specified offset with specified endian\nformat (writeFloatBE() writes big endian, writeFloatLE() writes little\nendian). value should be a valid 32-bit float. Behavior is undefined when\nvalue is anything other than a 32-bit float.
Setting noAssert to true allows the encoded form of value to extend beyond\nthe end of buf, but the resulting behavior is undefined.
const buf = Buffer.allocUnsafe(4);\n\nbuf.writeFloatBE(0xcafebabe, 0);\n\nconsole.log(buf);\n// Prints: <Buffer 4f 4a fe bb>\n\nbuf.writeFloatLE(0xcafebabe, 0);\n\nconsole.log(buf);\n// Prints: <Buffer bb fe 4a 4f>\nWrites value to buf at the specified offset. value should be a valid\nsigned 8-bit integer. Behavior is undefined when value is anything other than\na signed 8-bit integer.
Setting noAssert to true allows the encoded form of value to extend beyond\nthe end of buf, but the resulting behavior is undefined.
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>\nWrites value to buf at the specified offset with specified endian\nformat (writeInt16BE() writes big endian, writeInt16LE() writes little\nendian). value should be a valid signed 16-bit integer. Behavior is undefined\nwhen value is anything other than a signed 16-bit integer.
Setting noAssert to true allows the encoded form of value to extend beyond\nthe end of buf, but the resulting behavior is undefined.
value is interpreted and written as a two's complement signed integer.
const buf = Buffer.allocUnsafe(4);\n\nbuf.writeInt16BE(0x0102, 0);\nbuf.writeInt16LE(0x0304, 2);\n\nconsole.log(buf);\n// Prints: <Buffer 01 02 04 03>\nWrites value to buf at the specified offset with specified endian\nformat (writeInt16BE() writes big endian, writeInt16LE() writes little\nendian). value should be a valid signed 16-bit integer. Behavior is undefined\nwhen value is anything other than a signed 16-bit integer.
Setting noAssert to true allows the encoded form of value to extend beyond\nthe end of buf, but the resulting behavior is undefined.
value is interpreted and written as a two's complement signed integer.
const buf = Buffer.allocUnsafe(4);\n\nbuf.writeInt16BE(0x0102, 0);\nbuf.writeInt16LE(0x0304, 2);\n\nconsole.log(buf);\n// Prints: <Buffer 01 02 04 03>\nWrites value to buf at the specified offset with specified endian\nformat (writeInt32BE() writes big endian, writeInt32LE() writes little\nendian). value should be a valid signed 32-bit integer. Behavior is undefined\nwhen value is anything other than a signed 32-bit integer.
Setting noAssert to true allows the encoded form of value to extend beyond\nthe end of buf, but the resulting behavior is undefined.
value is interpreted and written as a two's complement signed integer.
const buf = Buffer.allocUnsafe(8);\n\nbuf.writeInt32BE(0x01020304, 0);\nbuf.writeInt32LE(0x05060708, 4);\n\nconsole.log(buf);\n// Prints: <Buffer 01 02 03 04 08 07 06 05>\nWrites value to buf at the specified offset with specified endian\nformat (writeInt32BE() writes big endian, writeInt32LE() writes little\nendian). value should be a valid signed 32-bit integer. Behavior is undefined\nwhen value is anything other than a signed 32-bit integer.
Setting noAssert to true allows the encoded form of value to extend beyond\nthe end of buf, but the resulting behavior is undefined.
value is interpreted and written as a two's complement signed integer.
const buf = Buffer.allocUnsafe(8);\n\nbuf.writeInt32BE(0x01020304, 0);\nbuf.writeInt32LE(0x05060708, 4);\n\nconsole.log(buf);\n// Prints: <Buffer 01 02 03 04 08 07 06 05>\nWrites byteLength bytes of value to buf at the specified offset.\nSupports up to 48 bits of accuracy. Behavior is undefined when value is\nanything other than a signed integer.
Setting noAssert to true allows the encoded form of value to extend beyond\nthe end of buf, but the resulting behavior is undefined.
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\nbuf.writeIntLE(0x1234567890ab, 0, 6);\n\nconsole.log(buf);\n// Prints: <Buffer ab 90 78 56 34 12>\nWrites byteLength bytes of value to buf at the specified offset.\nSupports up to 48 bits of accuracy. Behavior is undefined when value is\nanything other than a signed integer.
Setting noAssert to true allows the encoded form of value to extend beyond\nthe end of buf, but the resulting behavior is undefined.
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\nbuf.writeIntLE(0x1234567890ab, 0, 6);\n\nconsole.log(buf);\n// Prints: <Buffer ab 90 78 56 34 12>\nWrites value to buf at the specified offset. value should be a\nvalid unsigned 8-bit integer. Behavior is undefined when value is anything\nother than an unsigned 8-bit integer.
Setting noAssert to true allows the encoded form of value to extend beyond\nthe end of buf, but the resulting behavior is undefined.
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>\nWrites value to buf at the specified offset with specified endian\nformat (writeUInt16BE() writes big endian, writeUInt16LE() writes little\nendian). value should be a valid unsigned 16-bit integer. Behavior is\nundefined when value is anything other than an unsigned 16-bit integer.
Setting noAssert to true allows the encoded form of value to extend beyond\nthe end of buf, but the resulting behavior is undefined.
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\nbuf.writeUInt16LE(0xdead, 0);\nbuf.writeUInt16LE(0xbeef, 2);\n\nconsole.log(buf);\n// Prints: <Buffer ad de ef be>\nWrites value to buf at the specified offset with specified endian\nformat (writeUInt16BE() writes big endian, writeUInt16LE() writes little\nendian). value should be a valid unsigned 16-bit integer. Behavior is\nundefined when value is anything other than an unsigned 16-bit integer.
Setting noAssert to true allows the encoded form of value to extend beyond\nthe end of buf, but the resulting behavior is undefined.
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\nbuf.writeUInt16LE(0xdead, 0);\nbuf.writeUInt16LE(0xbeef, 2);\n\nconsole.log(buf);\n// Prints: <Buffer ad de ef be>\nWrites value to buf at the specified offset with specified endian\nformat (writeUInt32BE() writes big endian, writeUInt32LE() writes little\nendian). value should be a valid unsigned 32-bit integer. Behavior is\nundefined when value is anything other than an unsigned 32-bit integer.
Setting noAssert to true allows the encoded form of value to extend beyond\nthe end of buf, but the resulting behavior is undefined.
const buf = Buffer.allocUnsafe(4);\n\nbuf.writeUInt32BE(0xfeedface, 0);\n\nconsole.log(buf);\n// Prints: <Buffer fe ed fa ce>\n\nbuf.writeUInt32LE(0xfeedface, 0);\n\nconsole.log(buf);\n// Prints: <Buffer ce fa ed fe>\nWrites value to buf at the specified offset with specified endian\nformat (writeUInt32BE() writes big endian, writeUInt32LE() writes little\nendian). value should be a valid unsigned 32-bit integer. Behavior is\nundefined when value is anything other than an unsigned 32-bit integer.
Setting noAssert to true allows the encoded form of value to extend beyond\nthe end of buf, but the resulting behavior is undefined.
const buf = Buffer.allocUnsafe(4);\n\nbuf.writeUInt32BE(0xfeedface, 0);\n\nconsole.log(buf);\n// Prints: <Buffer fe ed fa ce>\n\nbuf.writeUInt32LE(0xfeedface, 0);\n\nconsole.log(buf);\n// Prints: <Buffer ce fa ed fe>\nWrites byteLength bytes of value to buf at the specified offset.\nSupports up to 48 bits of accuracy. Behavior is undefined when value is\nanything other than an unsigned integer.
Setting noAssert to true allows the encoded form of value to extend beyond\nthe end of buf, but the resulting behavior is undefined.
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\nbuf.writeUIntLE(0x1234567890ab, 0, 6);\n\nconsole.log(buf);\n// Prints: <Buffer ab 90 78 56 34 12>\nWrites byteLength bytes of value to buf at the specified offset.\nSupports up to 48 bits of accuracy. Behavior is undefined when value is\nanything other than an unsigned integer.
Setting noAssert to true allows the encoded form of value to extend beyond\nthe end of buf, but the resulting behavior is undefined.
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\nbuf.writeUIntLE(0x1234567890ab, 0, 6);\n\nconsole.log(buf);\n// Prints: <Buffer ab 90 78 56 34 12>\nAllocates a new Buffer using an array of octets.
// Creates a new Buffer containing the UTF-8 bytes of the string 'buffer'\nconst buf = new Buffer([0x62, 0x75, 0x66, 0x66, 0x65, 0x72]);\nAllocates a new Buffer using an array of octets.
// Creates a new Buffer containing the UTF-8 bytes of the string 'buffer'\nconst buf = new Buffer([0x62, 0x75, 0x66, 0x66, 0x65, 0x72]);\nStability: 0 - Deprecated: Use\nBuffer.from(arrayBuffer[, byteOffset [, length]])\ninstead.
This creates a view of the ArrayBuffer or SharedArrayBuffer without\ncopying the underlying memory. For example, when passed a reference to the\n.buffer property of a TypedArray instance, the newly created Buffer will\nshare the same allocated memory as the TypedArray.
The optional byteOffset and length arguments specify a memory range within\nthe arrayBuffer that will be shared by the Buffer.
const arr = new Uint16Array(2);\n\narr[0] = 5000;\narr[1] = 4000;\n\n// Shares memory with `arr`\nconst buf = new Buffer(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>\nStability: 0 - Deprecated: Use\nBuffer.from(arrayBuffer[, byteOffset [, length]])\ninstead.
This creates a view of the ArrayBuffer or SharedArrayBuffer without\ncopying the underlying memory. For example, when passed a reference to the\n.buffer property of a TypedArray instance, the newly created Buffer will\nshare the same allocated memory as the TypedArray.
The optional byteOffset and length arguments specify a memory range within\nthe arrayBuffer that will be shared by the Buffer.
const arr = new Uint16Array(2);\n\narr[0] = 5000;\narr[1] = 4000;\n\n// Shares memory with `arr`\nconst buf = new Buffer(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>\nCopies the passed buffer data onto a new Buffer instance.
const buf1 = new Buffer('buffer');\nconst buf2 = new Buffer(buf1);\n\nbuf1[0] = 0x61;\n\nconsole.log(buf1.toString());\n// Prints: auffer\nconsole.log(buf2.toString());\n// Prints: buffer\nCopies the passed buffer data onto a new Buffer instance.
const buf1 = new Buffer('buffer');\nconst buf2 = new Buffer(buf1);\n\nbuf1[0] = 0x61;\n\nconsole.log(buf1.toString());\n// Prints: auffer\nconsole.log(buf2.toString());\n// Prints: buffer\nStability: 0 - Deprecated: Use Buffer.alloc() instead (also see\nBuffer.allocUnsafe()).
Allocates a new Buffer of size bytes. If the size is larger than\nbuffer.constants.MAX_LENGTH or smaller than 0, a RangeError will be\nthrown. A zero-length Buffer will be created if size is 0.
Prior to Node.js 8.0.0, the underlying memory for Buffer instances\ncreated in this way is not initialized. The contents of a newly created\nBuffer are unknown and may contain sensitive data. Use\nBuffer.alloc(size) instead to initialize a Buffer\nto zeroes.
const buf = new Buffer(10);\n\nconsole.log(buf);\n// Prints: <Buffer 00 00 00 00 00 00 00 00 00 00>\nStability: 0 - Deprecated: Use Buffer.alloc() instead (also see\nBuffer.allocUnsafe()).
Allocates a new Buffer of size bytes. If the size is larger than\nbuffer.constants.MAX_LENGTH or smaller than 0, a RangeError will be\nthrown. A zero-length Buffer will be created if size is 0.
Prior to Node.js 8.0.0, the underlying memory for Buffer instances\ncreated in this way is not initialized. The contents of a newly created\nBuffer are unknown and may contain sensitive data. Use\nBuffer.alloc(size) instead to initialize a Buffer\nto zeroes.
const buf = new Buffer(10);\n\nconsole.log(buf);\n// Prints: <Buffer 00 00 00 00 00 00 00 00 00 00>\nStability: 0 - Deprecated:\nUse Buffer.from(string[, encoding]) instead.
Creates a new Buffer containing the given JavaScript string string. If\nprovided, the encoding parameter identifies the character encoding of string.
const buf1 = new Buffer('this is a tést');\nconst buf2 = new Buffer('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('ascii'));\n// Prints: this is a tC)st\nStability: 0 - Deprecated:\nUse Buffer.from(string[, encoding]) instead.
Creates a new Buffer containing the given JavaScript string string. If\nprovided, the encoding parameter identifies the character encoding of string.
const buf1 = new Buffer('this is a tést');\nconst buf2 = new Buffer('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('ascii'));\n// Prints: this is a tC)st\nReturns an un-pooled Buffer.
In order to avoid the garbage collection overhead of creating many individually\nallocated Buffer instances, by default allocations under 4KB are sliced from a\nsingle larger allocated object.
In the case where a developer may need to retain a small chunk of memory from a\npool for an indeterminate amount of time, it may be appropriate to create an\nun-pooled Buffer instance using SlowBuffer then copy out the relevant bits.
// Need to keep around a few small chunks of memory\nconst store = [];\n\nsocket.on('readable', () => {\n const data = socket.read();\n\n // Allocate for retained data\n const sb = SlowBuffer(10);\n\n // Copy the data into the new allocation\n data.copy(sb, 0, 0, 10);\n\n store.push(sb);\n});\nUse of SlowBuffer should be used only as a last resort after a developer\nhas observed undue memory retention in their applications.
Allocates a new Buffer of size bytes. If the size is larger than\nbuffer.constants.MAX_LENGTH or smaller than 0, a RangeError will be\nthrown. A zero-length Buffer will be created if size is 0.
The underlying memory for SlowBuffer instances is not initialized. The\ncontents of a newly created SlowBuffer are unknown and may contain sensitive\ndata. Use buf.fill(0) to initialize a SlowBuffer to zeroes.
const { SlowBuffer } = require('buffer');\n\nconst buf = new SlowBuffer(5);\n\nconsole.log(buf);\n// Prints: (contents may vary): <Buffer 78 e0 82 02 01>\n\nbuf.fill(0);\n\nconsole.log(buf);\n// Prints: <Buffer 00 00 00 00 00>\nAllocates a new Buffer of size bytes. If the size is larger than\nbuffer.constants.MAX_LENGTH or smaller than 0, a RangeError will be\nthrown. A zero-length Buffer will be created if size is 0.
The underlying memory for SlowBuffer instances is not initialized. The\ncontents of a newly created SlowBuffer are unknown and may contain sensitive\ndata. Use buf.fill(0) to initialize a SlowBuffer to zeroes.
const { SlowBuffer } = require('buffer');\n\nconst buf = new SlowBuffer(5);\n\nconsole.log(buf);\n// Prints: (contents may vary): <Buffer 78 e0 82 02 01>\n\nbuf.fill(0);\n\nconsole.log(buf);\n// Prints: <Buffer 00 00 00 00 00>\nReturns 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.
Note that this is a property on the buffer module returned by\nrequire('buffer'), not on the Buffer global or a Buffer instance.
An alias for buffer.constants.MAX_LENGTH
Note that this is a property on the buffer module returned by\nrequire('buffer'), not on the Buffer global or a Buffer instance.
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.
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: '?'\nBecause the Euro (€) sign is not representable in US-ASCII, it is replaced\nwith ? in the transcoded Buffer.
Note that this is a property on the buffer module returned by\nrequire('buffer'), not on the Buffer global or a Buffer instance.