Node.js includes an out-of-process debugging utility accessible via a\nV8 Inspector and built-in debugging client. To use it, start Node.js\nwith the inspect argument followed by the path to the script to debug; a\nprompt will be displayed indicating successful launch of the debugger:
$ node inspect myscript.js\n< Debugger listening on ws://127.0.0.1:9229/80e7a814-7cd3-49fb-921a-2e02228cd5ba\n< For help, see: https://nodejs.org/en/docs/inspector\n< Debugger attached.\nBreak on start in myscript.js:1\n> 1 (function (exports, require, module, __filename, __dirname) { global.x = 5;\n 2 setTimeout(() => {\n 3 console.log('world');\ndebug>\nThe Node.js debugger client is not a full-featured debugger, but simple step and\ninspection are possible.
\nInserting the statement debugger; into the source code of a script will\nenable a breakpoint at that position in the code:
// myscript.js\nglobal.x = 5;\nsetTimeout(() => {\n debugger;\n console.log('world');\n}, 1000);\nconsole.log('hello');\nOnce the debugger is run, a breakpoint will occur at line 3:
\n$ node inspect myscript.js\n< Debugger listening on ws://127.0.0.1:9229/80e7a814-7cd3-49fb-921a-2e02228cd5ba\n< For help, see: https://nodejs.org/en/docs/inspector\n< Debugger attached.\nBreak on start in myscript.js:1\n> 1 (function (exports, require, module, __filename, __dirname) { global.x = 5;\n 2 setTimeout(() => {\n 3 debugger;\ndebug> cont\n< hello\nbreak in myscript.js:3\n 1 (function (exports, require, module, __filename, __dirname) { global.x = 5;\n 2 setTimeout(() => {\n> 3 debugger;\n 4 console.log('world');\n 5 }, 1000);\ndebug> next\nbreak in myscript.js:4\n 2 setTimeout(() => {\n 3 debugger;\n> 4 console.log('world');\n 5 }, 1000);\n 6 console.log('hello');\ndebug> repl\nPress Ctrl + C to leave debug repl\n> x\n5\n> 2 + 2\n4\ndebug> next\n< world\nbreak in myscript.js:5\n 3 debugger;\n 4 console.log('world');\n> 5 }, 1000);\n 6 console.log('hello');\n 7\ndebug> .exit\nThe repl command allows code to be evaluated remotely. The next command\nsteps to the next line. Type help to see what other commands are available.
Pressing enter without typing a command will repeat the previous debugger\ncommand.
It is possible to watch expression and variable values while debugging. On\nevery breakpoint, each expression from the watchers list will be evaluated\nin the current context and displayed immediately before the breakpoint's\nsource code listing.
\nTo begin watching an expression, type watch('my_expression'). The command\nwatchers will print the active watchers. To remove a watcher, type\nunwatch('my_expression').
cont, c: Continue executionnext, n: Step nextstep, s: Step inout, o: Step outpause: Pause running code (like pause button in Developer Tools)setBreakpoint(), sb(): Set breakpoint on current linesetBreakpoint(line), sb(line): Set breakpoint on specific linesetBreakpoint('fn()'), sb(...): Set breakpoint on a first statement in\nfunctions bodysetBreakpoint('script.js', 1), sb(...): Set breakpoint on first line of\nscript.jsclearBreakpoint('script.js', 1), cb(...): Clear breakpoint in script.js\non line 1It is also possible to set a breakpoint in a file (module) that\nis not loaded yet:
\n$ node inspect main.js\n< Debugger listening on ws://127.0.0.1:9229/4e3db158-9791-4274-8909-914f7facf3bd\n< For help, see: https://nodejs.org/en/docs/inspector\n< Debugger attached.\nBreak on start in main.js:1\n> 1 (function (exports, require, module, __filename, __dirname) { const mod = require('./mod.js');\n 2 mod.hello();\n 3 mod.hello();\ndebug> setBreakpoint('mod.js', 22)\nWarning: script 'mod.js' was not loaded yet.\ndebug> c\nbreak in mod.js:22\n 20 // USE OR OTHER DEALINGS IN THE SOFTWARE.\n 21\n>22 exports.hello = function() {\n 23 return 'hello from module';\n 24 };\ndebug>\nbacktrace, bt: Print backtrace of current execution framelist(5): List scripts source code with 5 line context (5 lines before and\nafter)watch(expr): Add expression to watch listunwatch(expr): Remove expression from watch listwatchers: List all watchers and their values (automatically listed on each\nbreakpoint)repl: Open debugger's repl for evaluation in debugging script's contextexec expr: Execute an expression in debugging script's contextrun: Run script (automatically runs on debugger's start)restart: Restart scriptkill: Kill scriptscripts: List all loaded scriptsversion: Display V8's versionV8 Inspector integration allows attaching Chrome DevTools to Node.js\ninstances for debugging and profiling. It uses the\nChrome DevTools Protocol.
\nV8 Inspector can be enabled by passing the --inspect flag when starting a\nNode.js application. It is also possible to supply a custom port with that flag,\ne.g. --inspect=9222 will accept DevTools connections on port 9222.
To break on the first line of the application code, pass the --inspect-brk\nflag instead of --inspect.
$ node --inspect index.js\nDebugger listening on ws://127.0.0.1:9229/dc9010dd-f8b8-4ac5-a510-c1a114ec7d29\nFor help, see: https://nodejs.org/en/docs/inspector\n(In the example above, the UUID dc9010dd-f8b8-4ac5-a510-c1a114ec7d29\nat the end of the URL is generated on the fly, it varies in different\ndebugging sessions.)
\nIf the Chrome browser is older than 66.0.3345.0,\nuse inspector.html instead of js_app.html in the above URL.
Chrome DevTools doesn't support debugging worker threads yet.\nndb can be used to debug them.
", "type": "module", "displayName": "V8 inspector integration for Node.js" } ], "type": "misc", "displayName": "Advanced usage" } ] } ] }