NODE-26(1)

📦 version 26.8.2, in centos-stream 10

💖 NODE-26(1) 💖

okay bestie, so this is the manual page for node — like, the manual page NODE-26(1)? that's literally the one. we're doing this. grab a boba, we're learning the whole runtime. 🧋✨

✨ NAME ✨

node — a server-side JavaScript runtime. that's it. that's the whole vibe. 🫶

🌸 SYNOPSIS 🌸

okay so here's the shapes it comes in, keep these exactly, no cap:

node [options] [v8 options] [<program-entry-point> | -e string | --]
     [arguments ...]
node inspect, [<program-entry-point> | -e string | <host>:<port>] ...
node [--v8-options]

🦋 DESCRIPTION 🦋

so Node.js is a set of libraries for JavaScript that lets you use JS outside of the browser. its main character energy? creating simple, easy-to-build network clients and servers. lowkey iconic. 👑

and like — if you just run node with no arguments at all? it starts a REPL. a whole interactive vibe check with your code. 💅

🌈 OPTIONS 🌈

buckle up bestie, there's a lot of these and they're all important:

- — alias for stdin. it's the same deal as using - in other command-line utilities: the script gets read from stdin, and the rest of the options are passed to that script. 🍓
-- — marks the end of node options. everything after it goes to the script instead. and if there's no script filename or eval/print script supplied before this? then the next argument gets used as the script filename. periodt.
--abort-on-uncaught-exception — instead of just exiting, it aborts, which makes a core file get generated so you can do post-mortem analysis with a debugger (think lldb, gdb, and mdb). 🩺 and if you pass this flag, the behavior can still be set to not abort through process.setUncaughtExceptionCaptureCallback() (and through usage of the node:domain module that uses it). iykyk.
--allow-addons — so with the Permission Model on, the process can't use native addons by default, and attempts to do so throw an ERR_DLOPEN_DISABLED unless you explicitly pass the --allow-addons flag when starting Node.js. example time:

// Attempt to require an native addon
require('nodejs-addon-example');

$ node --permission --allow-fs-read=* index.js
node:internal/modules/cjs/loader:1319
  return process.dlopen(module, path.toNamespacedPath(filename));
                 ^

Error: Cannot load native addon because loading addons is disabled.
    at Module._extensions..node (node:internal/modules/cjs/loader:1319:18)
    at Module.load (node:internal/modules/cjs/loader:1091:32)
    at Module._load (node:internal/modules/cjs/loader:938:12)
    at Module.require (node:internal/modules/cjs/loader:1115:19)
    at require (node:internal/modules/helpers:130:18)
    at Object.<anonymous> (/home/index.js:1:15)
    at Module._compile (node:internal/modules/cjs/loader:1233:14)
    at Module._extensions..js (node:internal/modules/cjs/loader:1287:10)
    at Module.load (node:internal/modules/cjs/loader:1091:32)
    at Module._load (node:internal/modules/cjs/loader:938:12) {
  code: 'ERR_DLOPEN_DISABLED'
}

--allow-child-process — with the Permission Model on, the process can't spawn any child process by default. attempts throw an ERR_ACCESS_DENIED unless you explicitly pass the --allow-child-process flag when starting Node.js. example:

const childProcess = require('node:child_process');
// Attempt to bypass the permission
childProcess.spawn('node', ['-e', 'require("fs").writeFileSync("/new-file", "example")']);

$ node --permission --allow-fs-read=* index.js
node:internal/child_process:388
  const err = this._handle.spawn(options);
                                         ^
Error: Access to this API has been restricted
    at ChildProcess.spawn (node:internal/child_process:388:28)
    at node:internal/main/run_main_module:17:47 {
  code: 'ERR_ACCESS_DENIED',
  permission: 'ChildProcess'
}

heads up bestie 🫶 — the child_process.fork() API inherits the execution arguments from the parent process. so if Node.js is started with the Permission Model enabled and the --allow-child-process flag is set, any child process created using child_process.fork() will automatically receive all the relevant Permission Model flags. this also applies to child_process.spawn(), except there the flags get propagated via the NODE_OPTIONS environment variable rather than directly through the process arguments. not me knowing this for later 💀

--allow-ffi — with the Permission Model on, the process can't use FFI APIs by default. attempts to use FFI APIs throw an ERR_ACCESS_DENIED exception unless you explicitly pass the --allow-ffi flag when starting Node.js. also the node:ffi module requires the --experimental-ffi flag and is only available in builds with FFI support. example:

const { DynamicLibrary, suffix } = require('node:ffi');
const lib = new DynamicLibrary(`./mylib.${suffix}`);

$ node --permission --experimental-ffi index.js
Error: Access to this API has been restricted. Use --allow-ffi to manage permissions.
    at node:internal/main/run_main_module:17:47 {
  code: 'ERR_ACCESS_DENIED',
  permission: 'FFI'
}

--allow-fs-read — this flag configures file system read permissions using the Permission Model. the valid arguments are:
- * — to allow all FileSystemRead operations.
- multiple paths can be allowed using multiple --allow-fs-read flags. example: --allow-fs-read=/folder1/ --allow-fs-read=/folder2/

examples live in the File System Permissions documentation. also — the initializer module and custom --require modules have an implicit read permission. 🎀

$ node --permission -r custom-require.js -r custom-require-2.js index.js

so custom-require.js, custom-require-2.js, and index.js will be in the allowed read list by default:

process.permission.has('fs.read', 'index.js'); // true
process.permission.has('fs.read', 'custom-require.js'); // true
process.permission.has('fs.read', 'custom-require-2.js'); // true

--allow-fs-write — this flag configures file system write permissions using the Permission Model. valid arguments:
- * — to allow all FileSystemWrite operations.
- multiple paths can be allowed using multiple --allow-fs-write flags. example: --allow-fs-write=/folder1/ --allow-fs-write=/folder2/

ok this part matters: paths delimited by comma (,) are no longer allowed. when you pass a single flag with a comma, a warning will be displayed. 📢 examples are in the File System Permissions documentation.

--allow-inspector — with the Permission Model on, the process can't connect through the inspector protocol. attempts throw an ERR_ACCESS_DENIED unless you explicitly pass the --allow-inspector flag when starting Node.js. example:

const { Session } = require('node:inspector/promises');

const session = new Session();
session.connect();

$ node --permission index.js
Error: connect ERR_ACCESS_DENIED Access to this API has been restricted. Use --allow-inspector to manage permissions.
  code: 'ERR_ACCESS_DENIED',
}

--allow-net — with the Permission Model on, the process can't access the network by default. attempts throw an ERR_ACCESS_DENIED unless you explicitly pass the --allow-net flag when starting Node.js. example:

const http = require('node:http');
// Attempt to bypass the permission
const req = http.get('http://example.com', () => {});

req.on('error', (err) => {
  console.log('err', err);
});

$ node --permission index.js
Error: connect ERR_ACCESS_DENIED Access to this API has been restricted. Use --allow-net to manage permissions.
  code: 'ERR_ACCESS_DENIED',
}

--allow-openssl-store — with the Permission Model on, the process can't use OpenSSL STORE loaders by default — like, for example, to load a private key from a <URL> passed to crypto.createPrivateKey(). attempts throw an ERR_ACCESS_DENIED unless you explicitly pass the --allow-openssl-store flag. this permission can be dropped at runtime via permission.drop().

🚨 real talk bestie: this flag grants broad authority to configured OpenSSL STORE loaders. a loader may access files, devices, tokens, or the network. access performed by a loader is not constrained by the fs.read, fs.write, or net permission scopes. so like, use it with intention, ok?

--allow-wasi — with the Permission Model on, the process can't create any WASI instances by default. for security reasons, the call throws an ERR_ACCESS_DENIED unless you explicitly pass the flag --allow-wasi in the main Node.js process. example:

const { WASI } = require('node:wasi');
// Attempt to bypass the permission
new WASI({
  version: 'preview1',
  // Attempt to mount the whole filesystem
  preopens: {
    '/': '/',
  },
});

$ node --permission --allow-fs-read=* index.js

Error: Access to this API has been restricted
    at node:internal/main/run_main_module:30:49 {
  code: 'ERR_ACCESS_DENIED',
  permission: 'WASI',
}

--allow-worker — with the Permission Model on, the process can't create any worker threads by default. for security reasons, the call throws an ERR_ACCESS_DENIED unless you explicitly pass the flag --allow-worker in the main Node.js process. example:

const { Worker } = require('node:worker_threads');
// Attempt to bypass the permission
new Worker(__filename);

$ node --permission --allow-fs-read=* index.js

Error: Access to this API has been restricted
    at node:internal/main/run_main_module:17:47 {
  code: 'ERR_ACCESS_DENIED',
  permission: 'WorkerThreads'
}

okay that's the first chunk bestie, bestie don't leave yet — there's more parts coming 💜🦋

--build-sea=config — okay so this generates a single executable application from a JSON configuration file. The argument must be a path to the configuration file. If the path is not absolute, it is resolved relative to the current working directory. For configuration fields, cross-platform notes, and asset APIs, see the single executable application documentation. 🫶
--build-snapshot — this one is lowkey iconic: it generates a snapshot blob when the process exits and writes it to disk, which can be loaded later with --snapshot-blob. When building the snapshot, if --snapshot-blob is not specified, the generated blob will be written, by default, to snapshot.blob in the current working directory. Otherwise it will be written to the path specified by --snapshot-blob. ✨

$ echo "globalThis.foo = 'I am from the snapshot'" > snapshot.js

# Run snapshot.js to initialize the application and snapshot the
# state of it into snapshot.blob.
$ node --snapshot-blob snapshot.blob --build-snapshot snapshot.js

$ echo "console.log(globalThis.foo)" > index.js

# Load the generated snapshot and start the application from index.js.
$ node --snapshot-blob snapshot.blob index.js
I am from the snapshot

The v8.startupSnapshot API can be used to specify an entry point at snapshot building time, thus avoiding the need of an additional entry script at deserialization time:

$ echo "require('v8').startupSnapshot.setDeserializeMainFunction(() => console.log('I am from the snapshot'))" > snapshot.js
$ node --snapshot-blob snapshot.blob --build-snapshot snapshot.js
$ node --snapshot-blob snapshot.blob
I am from the snapshot

For more information, check out the v8.startupSnapshot API documentation. The snapshot currently only supports loading a single entrypoint during the snapshot building process, which can load built-in modules, but not additional user-land modules. Users can bundle their applications into a single script with their bundler of choice before building a snapshot. As it's complicated to ensure the serializability of all built-in modules, which are also growing over time, only a subset of the built-in modules are well tested to be serializable during the snapshot building process. The Node.js core test suite checks that a few fairly complex applications can be snapshotted. The list of built-in modules being captured by the built-in snapshot of Node.js is considered supported. When the snapshot builder encounters a built-in module that cannot be serialized, it may crash the snapshot building process. In that case a typical workaround would be to delay loading that module until runtime, using either v8.startupSnapshot.setDeserializeMainFunction() or v8.startupSnapshot.addDeserializeCallback(). If serialization for an additional module during the snapshot building process is needed, please file a request in the Node.js issue tracker and link to it in the tracking issue for user-land snapshots. 🦋

--build-snapshot-config — specifies the path to a JSON configuration file which configures snapshot creation behavior. The following options are currently supported:
- builder <string> — Required. Provides the name to the script that is executed before building the snapshot, as if --build-snapshot had been passed with builder as the main script name.
- withoutCodeCache <boolean> — Optional. Including the code cache reduces the time spent on compiling functions included in the snapshot at the expense of a bigger snapshot size and potentially breaking portability of the snapshot.

When using this flag, additional script files provided on the command line will not be executed and instead be interpreted as regular command line arguments. 💅

-c, --check — syntax check the script without executing. No running, just vibes and validation. ✅
--completion-bash — print source-able bash completion script for Node.js.

node --completion-bash > node_bash_completion
source node_bash_completion

Shell completion? We love convenience. 🎀

-C condition, --conditions=condition — provide custom conditional exports resolution conditions. Any number of custom string condition names are permitted. The default Node.js conditions of "node", "default", "import", and "require" will always apply as defined. For example, to run a module with "development" resolutions:

node -C development app.js

Conditional exports girlies rise up. 🫶

--cpu-prof — starts the V8 CPU profiler on start up, and writes the CPU profile to disk before exit. If --cpu-prof-dir is not specified, the generated profile is placed in the current working directory. If --cpu-prof-name is not specified, the generated profile is named CPU.${yyyymmdd}.${hhmmss}.${pid}.${tid}.${seq}.cpuprofile.

$ node --cpu-prof index.js
$ ls *.cpuprofile
CPU.20190409.202950.15293.0.0.cpuprofile

If --cpu-prof-name is specified, the provided value is used as a template for the file name. The following placeholder is supported and will be substituted at runtime:

${pid} — the current process ID

$ node --cpu-prof --cpu-prof-name 'CPU.${pid}.cpuprofile' index.js
$ ls *.cpuprofile
CPU.15293.cpuprofile

Profile it, bestie. Your performance tea is piping hot. 🔥

--cpu-prof-dir — specify the directory where the CPU profiles generated by --cpu-prof will be placed. The default value is controlled by the --diagnostic-dir command-line option. 📁
--cpu-prof-interval — specify the sampling interval in microseconds for the CPU profiles generated by --cpu-prof. The default is 1000 microseconds. ⏱️
--cpu-prof-name — specify the file name of the CPU profile generated by --cpu-prof. 🏷️
--diagnostic-dir=directory — set the directory to which all diagnostic output files are written. Defaults to current working directory. Affects the default output directory of:
- --cpu-prof-dir
- --heap-prof-dir
- --redirect-warnings

One folder to rule the diagnostic output. 🧚

--disable-proto=mode — disable the Object.prototype.__proto__ property. If mode is delete, the property is removed entirely. If mode is throw, accesses to the property throw an exception with the code ERR_PROTO_ACCESS. Careful, this is a real behavior change, not a drill. 💀
--disable-sigusr1 — disable the ability of starting a debugging session by sending a SIGUSR1 signal to the process. No surprise debug sessions, thank you very much. 🙈
--disable-warning=code-or-type — disable specific process warnings by code or type. Warnings emitted from process.emitWarning() may contain a code and a type. This option will not-emit warnings that have a matching code or type. There's a List of deprecation warnings if you need the receipts. The Node.js core warning types are: DeprecationWarning and ExperimentalWarning.

For example, the following script will not emit DEP0025 require('node:sys') when executed with node --disable-warning=DEP0025:

import sys from 'node:sys';

const sys = require('node:sys');

For example, the following script will emit the DEP0025 require('node:sys'), but not any Experimental Warnings (such as ExperimentalWarning: vm.measureMemory is an experimental feature in <=v21) when executed with node --disable-warning=ExperimentalWarning:

import sys from 'node:sys';
import vm from 'node:vm';

vm.measureMemory();

const sys = require('node:sys');
const vm = require('node:vm');

vm.measureMemory();

Silence the warnings you truly don't need. Filtered, not ignored. 💅

--disable-wasm-trap-handler — okay bestie, this is a whole saga. Node.js enables V8's trap-handler-based WebAssembly bound checks on 64-bit platforms, which significantly improves WebAssembly performance by eliminating the need for inline bound checks. This optimization requires allocating a large virtual memory cage per WebAssembly memory instance (currently typically 8GB for 32-bit WebAssembly memory, 16GB for 64-bit WebAssembly memory) to trap out-of-bound accesses. On most 64-bit platforms, the virtual memory address space is usually large enough (around 128TB) to accommodate typical WebAssembly usages, but if the machine has manual limits on virtual memory (e.g. through ulimit -v), WebAssembly memory allocation is more likely to fail with WebAssembly.Memory(): could not allocate memory.

At startup, Node.js automatically checks whether there is enough virtual memory available to allocate at least one cage, and if not, the trap-handler optimization is automatically disabled so that WebAssembly can still run using inline bound checks (with less optimal performance). But if the application needs to create many WebAssembly memory instances and the machine still configures a relatively high limit on virtual memory, allocation of WebAssembly memory instances may still fail more quickly than expected due to the raised virtual memory usage.

--disable-wasm-trap-handler fully disables this optimization so that WebAssembly memory instances always use inline bound checks instead of reserving large virtual memory cages. This allows more instances to be created when the virtual memory address space available to the Node.js process is limited. 🌈

--disallow-code-generation-from-strings — make built-in language features like eval and new Function that generate code from strings throw an exception instead. This does not affect the Node.js node:vm module. String-to-code shenanigans? Blocked. 🚫
--dns-result-order=order — set the default value of order in dns.lookup() and dnsPromises.lookup(). The value could be:
- ipv4first: sets default order to ipv4first.
- ipv6first: sets default order to ipv6first.
- verbatim: sets default order to verbatim.

The default is verbatim and dns.setDefaultResultOrder() have higher priority than --dns-result-order. DNS order: chosen with intention. 🌐

--enable-fips — enable FIPS mode at startup. With OpenSSL 3, a configured provider named fips must be available and initialize successfully. With OpenSSL 1.1.1, Node.js must be built against a FIPS-capable OpenSSL. Compliance era, activated. 👑
--enable-source-maps — ok so this one is literally a lifesaver if you're out here using a transpiler (looking at you, TypeScript 👀). Without it, when your app throws a stack trace, the trace points at the transpiled code, not where the source actually lives. Turning this on enables caching of Source Maps and makes a best effort to report stack traces relative to the original source file. 💅 One catch tho: overriding Error.prepareStackTrace may prevent --enable-source-maps from modifying the stack trace. If you do override it, pls call and return the results of the original Error.prepareStackTrace inside your function so source maps can still do their thing:

const originalPrepareStackTrace = Error.prepareStackTrace;
Error.prepareStackTrace = (error, trace) => {
  // Modify error and trace and format stack trace with
  // original Error.prepareStackTrace.
  return originalPrepareStackTrace(error, trace);
};

heads up bestie 🫶 enabling source maps can introduce latency to your application when Error.stack is accessed. If you're accessing Error.stack a lot, pls take the performance implications of --enable-source-maps into account. no cap.

--entry-url — when present, Node.js will interpret the entry point as a URL, rather than a path. It follows ECMAScript module resolution rules, and any query parameter or hash in the URL will be accessible via import.meta.url. slay.

node --entry-url 'file:///path/to/file.js?queryparams=work#and-hashes-too'
node --entry-url 'file.ts?query#hash'
node --entry-url 'data:text/javascript,console.log("Hello")'

--env-file-if-exists=file — behavior is the same as --env-file, but an error is not thrown if the file does not exist. it's giving "no pressure" energy 🦋.
--env-file=file — loads environment variables from a file relative to the current directory, making them available to applications on process.env. The environment variables which configure Node.js, such as NODE_OPTIONS, are parsed and applied. If the same variable is defined in the environment and in the file, the value from the environment takes precedence. You can pass multiple --env-file arguments, and subsequent files override pre-existing variables defined in previous files. An error is thrown if the file does not exist.

node --env-file=.env --env-file=.development.env index.js

The format of the file should be one line per key-value pair of environment variable name and value separated by =:

PORT=3000

Any text after a # is treated as a comment:

# This is a comment
PORT=3000 # This is also a comment

Values can start and end with the following quotes: `, " or '. They are omitted from the values.

USERNAME="nodejs" # will result in `nodejs` as the value.

Multi-line values are supported:

MULTI_LINE="THIS IS
A MULTILINE"
# will result in `THIS IS\nA MULTILINE` as the value.

The export keyword before a key is ignored:

export USERNAME="nodejs" # will result in `nodejs` as the value.

If you want to load environment variables from a file that may not exist, you can use the --env-file-if-exists flag instead. ✨

-e, --eval script — evaluate the following argument as JavaScript. The modules which are predefined in the REPL can also be used in script. If script starts with -, pass it using = (for example, node --print --eval=-42) so it is parsed as the value of --eval. 🧚 On Windows, using cmd.exe a single quote will not work correctly because it only recognizes double " for quoting. In Powershell or Git bash, both ' and " are usable. It is possible to run code containing inline types unless the --no-strip-types flag is provided.
--experimental-addon-modules — enable experimental import support for .node addons. 🔥
--experimental-config-file=path, --experimental-config-file — if present, Node.js will look for a configuration file at the specified path. If the path is not specified, Node.js will look for a node.config.json file in the current working directory. To specify a custom path, use the --experimental-config-file=path form. The space-separated --experimental-config-file path form is not supported. The alias --experimental-default-config-file is equivalent to --experimental-config-file without an argument. Node.js will read the configuration file and apply the settings. The configuration file should be a JSON file with the following structure. vX.Y.Z in the $schema must be replaced with the version of Node.js you are using or latest-vX.x for the latest version of that major release line.

{
  "$schema": "https://nodejs.org/dist/vX.Y.Z/docs/node-config-schema.json",
  "nodeOptions": {
    "import": [
      "amaro/strip"
    ],
    "watch-path": "src",
    "watch-preserve-output": true
  },
  "test": {
    "test-isolation": "process"
  },
  "watch": {
    "watch-preserve-output": true
  }
}

The configuration file supports namespace-specific options:

The nodeOptions field contains CLI flags that are allowed in NODE_OPTIONS.
Namespace fields like test, watch, and permission contain configuration specific to that subsystem.

The configuration file can target a specific Node.js major version with nodeVersion:

{
  "nodeVersion": 25,
  "nodeOptions": {
    "watch-path": "src"
  }
}

To keep multiple version-specific configurations in the same file, use the configs array. Node.js will use the first entry whose nodeVersion matches the current Node.js major version:

{
  "$schema": "https://nodejs.org/dist/latest-v26.x/docs/node-config-schema.json",
  "configs": [
    {
      "nodeVersion": 25,
      "config": {
        "$schema": "https://nodejs.org/dist/latest-v25.x/docs/node-config-schema.json",
        "nodeOptions": {
          "watch-path": "src"
        }
      }
    }
  ]
}

When configs is used, the top level may only contain $schema and configs. Each configs item must define an integer nodeVersion and an object config. A single top-level config does not require nodeVersion, but if present it must match the current Node.js major version. When a namespace is present in the configuration file, Node.js automatically enables the corresponding flag (e.g., --test, --watch, --permission). This allows you to configure subsystem-specific options without explicitly passing the flag on the command line. For example:

{
  "test": {
    "test-isolation": "process"
  }
}

is equivalent to:

node --test --test-isolation=process

To disable the automatic flag while still using namespace options, you can explicitly set the flag to false within the namespace:

{
  "test": {
    "test": false,
    "test-isolation": "process"
  }
}

No-op flags are not supported. Not all V8 flags are currently supported. It is possible to use the official JSON schema to validate the configuration file, which may vary depending on the Node.js version. Each key in the configuration file corresponds to a flag that can be passed as a command-line argument. The value of the key is the value that would be passed to the flag. For example, the configuration file above is equivalent to the following command-line arguments:

node --import amaro/strip --watch-path=src --watch-preserve-output --test-isolation=process

The priority in configuration is as follows:

NODE_OPTIONS and command-line options
Dotenv NODE_OPTIONS
Configuration file

Values in the configuration file will not override the values in the environment variables, command-line options, or the NODE_OPTIONS env file parsed by the --env-file flag. Keys cannot be duplicated within the same or different namespaces. The configuration parser will throw an error if the configuration file contains unknown keys or keys that cannot be used in a namespace.

⚠️ HUGE one: Node.js will not sanitize or perform validation on the user-provided configuration, so NEVER use untrusted configuration files. like, ever. fr fr. 💀

--experimental-default-config-file — this flag is an alias for --experimental-config-file without an argument. If present, Node.js will look for a node.config.json file in the current working directory and load it as a configuration file. 🎀
--experimental-eventsource — enable exposition of EventSource Web API on the global scope. iconic.
--experimental-ffi — enable the experimental node:ffi module. This flag is only available in builds with FFI support. 🦋
--experimental-import-meta-resolve — enable experimental import.meta.resolve() parent URL support, which allows passing a second parentURL argument for contextual resolution. Previously gated the entire import.meta.resolve feature. iykyk.
--experimental-import-text — enable experimental support for importing modules with with { type: 'text' }. ✨
--experimental-inspector-network-resource — enable experimental support for inspector network resources.
--experimental-loader=module — specify the module containing exported asynchronous module customization hooks. module may be any string accepted as an import specifier. This feature requires --allow-worker if used with the Permission Model. 👑
--experimental-network-inspection — enable experimental support for the network inspection with Chrome DevTools. cute AND useful.

--experimental-package-map=<path> — turns on experimental package map resolution, bestie ✨. The path argument is the location of a JSON configuration file that defines package resolution mappings.

node --experimental-package-map=./package-map.json app.js

When it's enabled, bare specifier resolution consults the package map for resolution. That means you get explicit control over which packages can import which dependencies 👑. See Package maps for the details on the configuration file format and the resolution algorithm. iykyk 💅

--experimental-print-required-tla — if the ES module graph can't be require()'d because it contains any top-level await, this flag lets Node.js locate them and print their locations 📍. Not me debugging for three hours when this exists 😭.
--experimental-quic — enable experimental support for the QUIC protocol 🦋.
--experimental-sea-config — use this flag to generate a blob that can be injected into the Node.js binary to produce a single executable application 🌈. See the documentation about this configuration for details.
--experimental-shadow-realm — use this flag to enable ShadowRealm support ✨.
--experimental-storage-inspection — enable experimental support for storage inspection 🎀.
--experimental-stream-iter — enable the experimental node:stream/iter module 🌸.
--experimental-test-coverage — when used in conjunction with the node:test module, a code coverage report is generated as part of the test runner output 📊. If no tests are run, a coverage report is not generated. See the documentation on collecting code coverage from tests for more details.
--experimental-test-module-mocks — enable module mocking in the test runner 🧚. This feature requires --allow-worker if used with the Permission Model. Don't forget, okay?
--experimental-test-tag-filter='<expr>' — run only the tests that match the boolean tag-filter expression you passed 💅. Tests declare tags via the tags option on test(), it(), suite(), or describe(). Tags inherit from suites to nested tests by union.

The expression supports boolean operators (and/&&, or/||, not/!), parentheses for grouping, and * wildcards inside identifiers. Standard precedence applies: not binds tighter than and, which binds tighter than or. See Test tags for the full grammar and behavior.

The flag may be specified more than once; multiple expressions are combined with AND, so a test must satisfy every expression to run 🔥. A malformed expression causes the test runner to exit with a non-zero status before running any tests. fr fr, it just bails 💀.

--experimental-vfs — enable the experimental node:vfs module 🦋.
--experimental-vm-modules — enable experimental ES Module support in the node:vm module.
--experimental-wasi-unstable-preview1 — enable experimental WebAssembly System Interface (WASI) support 🌈.
--experimental-worker-inspection — enable experimental support for worker inspection with Chrome DevTools 🔍.
--force-context-aware — disable loading native addons that are not context-aware 🚫.
--force-fips — enable FIPS mode at startup and prevent it from being disabled from script code 🔒. The same OpenSSL requirements as --enable-fips apply.
--force-node-api-uncaught-exceptions-policy — enforces the uncaughtException event on Node-API asynchronous callbacks 🫶. To prevent an existing add-on from crashing the process, this flag is not enabled by default. In the future, this flag will be enabled by default to enforce the correct behavior. So it's giving "get ahead of it" energy ✨.
--frozen-intrinsics — enable experimental frozen intrinsics like Array and Object 🧊. Only the root context is supported. There is no guarantee that globalThis.Array is indeed the default intrinsic reference.

Code may break under this flag 💀. That's not a vibe, that's a warning, bestie.

To allow polyfills to be added, --require and --import both run before freezing intrinsics 👑

--heap-prof — starts the V8 heap profiler on start up, and writes the heap profile to disk before exit 🎀. If --heap-prof-dir is not specified, the generated profile is placed in the current working directory. If --heap-prof-name is not specified, the generated profile is named Heap.${yyyymmdd}.${hhmmss}.${pid}.${tid}.${seq}.heapprofile.

$ node --heap-prof index.js
$ ls *.heapprofile
Heap.20190409.202950.15293.0.001.heapprofile

--heap-prof-dir — specify the directory where the heap profiles generated by --heap-prof will be placed 📁. The default value is controlled by the --diagnostic-dir command-line option.
--heap-prof-interval — specify the average sampling interval in bytes for the heap profiles generated by --heap-prof. The default is 512 * 1024 bytes.
--heap-prof-name — specify the file name of the heap profile generated by --heap-prof 🏷️.
--heapsnapshot-near-heap-limit=max_count — writes a V8 heap snapshot to disk when the V8 heap usage is approaching the heap limit 📸. count should be a non-negative integer (in which case Node.js will write no more than max_count snapshots to disk).

When generating snapshots, garbage collection may be triggered and bring the heap usage down. Therefore multiple snapshots may be written to disk before the Node.js instance finally runs out of memory 😭. These heap snapshots can be compared to determine what objects are being allocated during the time consecutive snapshots are taken.

It's not guaranteed that Node.js will write exactly max_count snapshots to disk, but it will try its best to generate at least one and up to max_count snapshots before the Node.js instance runs out of memory when max_count is greater than 0.

Generating V8 snapshots takes time and memory (both memory managed by the V8 heap and native memory outside the V8 heap) 💀. The bigger the heap is, the more resources it needs. Node.js will adjust the V8 heap to accommodate the additional V8 heap memory overhead, and try its best to avoid using up all the memory available to the process. When the process uses more memory than the system deems appropriate, the process may be terminated abruptly by the system, depending on the system configuration. scary but true 🙈.

$ node --max-old-space-size=100 --heapsnapshot-near-heap-limit=3 index.js
Wrote snapshot to Heap.20200430.100036.49580.0.001.heapsnapshot
Wrote snapshot to Heap.20200430.100037.49580.0.002.heapsnapshot
Wrote snapshot to Heap.20200430.100038.49580.0.003.heapsnapshot

<--- Last few GCs --->

[49580:0x110000000]     4826 ms: Mark-sweep 130.6 (147.8) -> 130.5 (147.8) MB, 27.4 / 0.0 ms  (average mu = 0.126, current mu = 0.034) allocation failure scavenge might not succeed
[49580:0x110000000]     4845 ms: Mark-sweep 130.6 (147.8) -> 130.6 (147.8) MB, 18.8 / 0.0 ms  (average mu = 0.088, current mu = 0.031) allocation failure scavenge might not succeed

<--- JS stacktrace --->

FATAL ERROR: Ineffective mark-compacts near heap limit Allocation failed - JavaScript heap out of memory

--heapsnapshot-signal=signal — enables a signal handler that causes the Node.js process to write a heap dump when the specified signal is received 📡. signal must be a valid signal name. Disabled by default.

$ node --heapsnapshot-signal=SIGUSR2 index.js &
$ ps aux
USER       PID %CPU %MEM    VSZ   RSS TTY      STAT START   TIME COMMAND
node         1  5.5  6.1 787252 247004 ?       Ssl  16:43   0:02 node --heapsnapshot-signal=SIGUSR2 index.js
$ kill -USR2 1
$ ls
Heap.20190718.133405.15554.0.001.heapsnapshot

-h, --help — print node command-line options 🌸. The output of this option is less detailed than this document, so like… it's the TL;DR version bestie 💅.
--icu-data-dir=file — specify ICU data load path. (Overrides NODE_ICU_DATA.) 🌈
--import=module — preload the specified module at startup 🫶. If the flag is provided several times, each module will be executed sequentially in the order they appear, starting with the ones provided in NODE_OPTIONS. Follows ECMAScript module resolution rules.

Use --require to load a CommonJS module. Modules preloaded with --require will run before modules preloaded with --import. Modules are preloaded into the main thread as well as any worker threads, forked processes, or clustered processes 🔥.

--input-type=type — this configures Node.js to interpret --eval or STDIN input as CommonJS or as an ES module 🎀. Valid values are "commonjs", "module", "module-typescript" and "commonjs-typescript". The "-typescript" values are not available with the flag --no-strip-types. The default is no value, or "commonjs" if --no-experimental-detect-module is passed.

If --input-type is not provided, Node.js will try to detect the syntax with the following steps:

Run the input as CommonJS.
If step 1 fails, run the input as an ES module.
If step 2 fails with a SyntaxError, strip the types.
If step 3 fails with an error code ERR_UNSUPPORTED_TYPESCRIPT_SYNTAX or ERR_INVALID_TYPESCRIPT_SYNTAX, throw the error from step 2, including the TypeScript error in the message, else run as CommonJS.
If step 4 fails, run the input as an ES module.

To avoid the delay of multiple syntax detection passes, the --input-type=type flag can be used to specify how the --eval input should be interpreted ✨. The REPL does not support this option. Usage of --input-type=module with --print will throw an error, as --print does not support ES module syntax 💀.

--insecure-http-parser — enable leniency flags on the HTTP parser 🙈. This may allow interoperability with non-conformant HTTP implementations. When enabled, the parser will accept the following:
- Invalid HTTP headers values.
- Invalid HTTP versions.
- Allow message containing both Transfer-Encoding and Content-Length headers.
- Allow extra data after message when Connection: close is present.
Allow extra transfer encodings after chunked has been provided.
- Allow \n to be used as token separator instead of \r\n.
- Allow \r\n not to be provided after a chunk.
- Allow spaces to be present after a chunk size and before \r\n.

okay bestie, real talk: all the above will expose your application to request smuggling or poisoning attack. Avoid using this option. like, avoid it avoid it. 💀

--inspect-brk=[[host:]port] — activates the inspector on host:port and breaks at the start of your user script (so you get to watch it from line one, main character energy ✨). Default host:port is 127.0.0.1:9229. If you pass port 0, a random available port gets picked for you 🎲. See V8 Inspector integration for Node.js for further explanation on the Node.js debugger. And pls check the security warning below about the host parameter — iykyk 🫶
--inspect-port=[host:]port — sets the host:port to be used when the inspector is activated. Super useful when you're activating the inspector by sending the SIGUSR1 signal. Except when --disable-sigusr1 is passed 👀. Default host is 127.0.0.1. Port 0 = random available port, love that for you 🎀. See the security warning below regarding the host parameter usage.
--inspect-publish-uid=stderr,http — specifies the ways the inspector web socket url gets exposed. By default the inspector websocket url is available in stderr and under the /json/list endpoint on http://host:port/json/list 🦋
--inspect-wait=[[host:]port] — activates the inspector on host:port and waits for a debugger to be attached before anything happens (it's giving "not me waiting by the phone" 😭). Default host:port is 127.0.0.1:9229. Port 0 → random available port 🌸. See V8 Inspector integration for Node.js for further explanation on the Node.js debugger. See the security warning below regarding the host parameter usage.
--inspect=[[host:]port] — activates the inspector on host:port. Default is 127.0.0.1:9229. If port 0 is specified, a random available port will be used ✨. V8 inspector integration lets tools like Chrome DevTools and IDEs debug and profile Node.js instances — the tools attach to Node.js instances via a tcp port and communicate using the Chrome DevTools Protocol. See V8 Inspector integration for Node.js for further explanation on the Node.js debugger 🔍
-i, --interactive — opens the REPL even if stdin does not appear to be a terminal. like, it's doing it anyway, bestie 💅
--jitless — disables runtime allocation of executable memory. This may be required on some platforms for security reasons 🔒. It can also reduce attack surface on other platforms, but the performance impact may be severe — no cap, that's the tradeoff 😬
--localstorage-file=file — the file used to store localStorage data. If the file does not exist, it is created the first time localStorage is accessed 🍓. The same file may be shared between multiple Node.js processes concurrently — yes, concurrently, they're sharing, it's a whole vibe 🫶
--max-http-header-size=size — specify the maximum size, in bytes, of HTTP headers. Defaults to 16 KiB 📏
--max-old-space-size-percentage=percentage — sets the maximum memory size of V8's old memory section as a percentage of available system memory. This flag takes precedence over --max-old-space-size when both are specified 👑. The percentage parameter must be a number greater than 0 and up to 100, representing the percentage of available system memory to allocate to the V8 heap. Note: this flag utilizes --max-old-space-size, which may be unreliable on 32-bit platforms due to integer overflow issues ⚠️

# Using 50% of available system memory
node --max-old-space-size-percentage=50 index.js

# Using 75% of available system memory
node --max-old-space-size-percentage=75 index.js

--network-family-autoselection-attempt-timeout — sets the default value for the network family autoselection attempt timeout ⏱️. For more information, see net.getDefaultAutoSelectFamilyAttemptTimeout().
--no-addons — disables the node-addons exports condition as well as disables loading native addons. When --no-addons is specified, calling process.dlopen or requiring a native C++ addon will fail and throw an exception 🙈
--no-async-context-frame — disables the use of AsyncLocalStorage backed by AsyncContextFrame and uses the prior implementation which relied on async_hooks. The previous model is retained for compatibility with Electron and for cases where the context flow may differ 🧚. However, if a difference in flow is found please report it — they literally want to know, fr fr 🫶
--no-deprecation — silences deprecation warnings 🤫
--no-experimental-detect-module — disables using syntax detection to determine module type 🔍
--no-experimental-global-navigator — disables exposition of the Navigator API on the global scope 🌐
--no-experimental-repl-await — use this flag to disable top-level await in the REPL ⏳
--no-experimental-require-module — legacy alias for --no-require-module 🏷️
--no-experimental-sqlite — disables the experimental node:sqlite module 🗄️
--no-experimental-websocket — disables exposition of <WebSocket> on the global scope 🔌
--no-experimental-webstorage — disables Web Storage support 📦
--no-extra-info-on-fatal-exception — hides the extra information on a fatal exception that causes exit 💀
--no-force-async-hooks-checks — disables runtime checks for async_hooks. These will still be enabled dynamically when async_hooks is enabled ✨
--no-global-search-paths — do not search modules from global paths like $HOME/.node_modules and $NODE_PATH 🚫
--no-network-family-autoselection — disables the family autoselection algorithm unless connection options explicitly enable it 🔗
--no-require-module — disables support for loading a synchronous ES module graph in require(). See Loading ECMAScript modules using require() 📚
--no-strip-types — disables type-stripping for TypeScript files. For more information, see the TypeScript type-stripping documentation 🟦
--no-warnings — silences all process warnings (including deprecations) 🔇
--node-memory-debug — enables extra debug checks for memory leaks in Node.js internals. This is usually only useful for developers debugging Node.js itself 🛠️ (like, you'll know if this is you)
--openssl-config=file — loads an OpenSSL configuration file on startup. The file can activate an OpenSSL 3 FIPS provider or configure a FIPS-capable OpenSSL 1.1.1 build. See FIPS mode 🔐. This option takes precedence over the OPENSSL_CONF environment variable 👑
--openssl-legacy-provider — enables the OpenSSL 3.0 legacy provider. For more information please see OSSL_PROVIDER-legacy 🗝️
--openssl-shared-config — enables the OpenSSL default configuration section, openssl_conf, to be read from the OpenSSL configuration file. The default configuration file is named openssl.cnf but this can be changed using the environment variable OPENSSL_CONF, or by using the command line option --openssl-config 🎀. The location of the default OpenSSL configuration file depends on how OpenSSL is being linked to Node.js. Sharing the OpenSSL configuration may have unwanted implications, and it is recommended to use a configuration section specific to Node.js, which is nodejs_conf and is default when this option is not used ⚠️
--pending-deprecation — emits pending deprecation warnings 📢. Pending deprecations are generally identical to a runtime deprecation with the notable exception that they are turned off by default and will not be emitted unless either the --pending-deprecation command-line flag, or the NODE_PENDING_DEPRECATION=1 environment variable, is set. Pending deprecations are used to provide a kind of selective "early warning" mechanism that developers may leverage to detect deprecated API usage 🚨
--permission — enables the Permission Model for the current process. When enabled, the following permissions are restricted 🔒:
- File System — manageable through --allow-fs-read, --allow-fs-write flags 📁
- Network — manageable through --allow-net flag 🌐
- Child Process — manageable through --allow-child-process flag 👶
- Worker Threads — manageable through --allow-worker flag 🧵
- WASI — manageable through --allow-wasi flag 🧩
- Addons — manageable through --allow-addons flag 🔧
- FFI — manageable through --allow-ffi flag 🔗
- OpenSSL STORE loaders — manageable through --allow-openssl-store flag 🗄️
--permission-audit — enables audit mode for the permission model 👀. When enabled, permission checks are performed but access is not denied — no ERR_ACCESS_DENIED error is thrown. Instead, each permission violation is published through the node:diagnostics_channel module, and execution continues normally ✨. This flag does not require --permission to be specified. The --allow-* flags are not needed in audit mode, since no access is denied. Audit mode is useful for discovering what permissions your application requires before deploying with --permission 🕵️. See the Permission Model documentation for the list of diagnostics channel names and the message format. If both --permission and --permission-audit are specified, --permission takes precedence and the Permission Model runs in enforce mode 👑
--preserve-symlinks — instructs the module loader to preserve symbolic links when resolving and caching modules 🔗. By default, when Node.js loads a module from a path that is symbolically linked to a different on-disk location, Node.js will dereference the link and use the actual on-disk "real path" of the module as both an identifier and as a root path to locate other dependency modules. In most cases, this default behavior is acceptable 🫶. However, when using symbolically linked peer dependencies, as illustrated in the example below, the default behavior causes an exception to be thrown if moduleA attempts to require moduleB as a peer dependency:

{appDir}
├── app
│   ├── index.js
│   └── node_modules
│       ├── moduleA -> {appDir}/moduleA
│       └── moduleB
│           ├── index.js
│           └── package.json
└── moduleA
    ├── index.js
    └── package.json

okay so that's the whole layout we're talking about ✨ and here's the tea: the --preserve-symlinks command-line flag tells Node.js to use the symlink path for modules instead of the real path, which is literally what lets symbolically linked peer dependencies actually get found. bestie, that's the whole point 🫶

but wait — --preserve-symlinks can have other side effects, no cap. Specifically: symbolically linked native modules can fail to load if those are linked from more than one location in the dependency tree. why? because Node.js would see those as two separate modules and would attempt to load the module multiple times, causing an exception to be thrown 💀 so like, it's giving "works until it doesn't".

Also important: the --preserve-symlinks flag does not apply to the main module, which is what allows node --preserve-symlinks node_module/.bin/<foo> to work. To get that same behavior for the main module, you also use --preserve-symlinks-main. iykyk 🎀

✨ `--preserve-symlinks-main` ✨

Instructs the module loader to preserve symbolic links when resolving and caching the main module (require.main). 💅

This flag exists so that the main module can be opted-in to the same behavior that --preserve-symlinks gives to all other imports. they are separate flags, however, for backward compatibility with older Node.js versions. so don't come for me about it 🙈

--preserve-symlinks-main does not imply --preserve-symlinks. use --preserve-symlinks-main in addition to --preserve-symlinks when it is not desirable to follow symlinks before resolving relative paths. and yeah, see --preserve-symlinks for more information, it's right above ⬆️

✨ `-p`, `--print script` ✨

Identical to -e but prints the result. that's it, that's the whole flag. short, sweet, slays 🌸

✨ `--prof` ✨

Generate V8 profiler output. 🔥

✨ `--prof-process` ✨

Process V8 profiler output generated using the V8 option --prof. so like, --prof makes the snack, --prof-process eats it 🍓

✨ `--redirect-warnings=file` ✨

Write process warnings to the given file instead of printing to stderr. 📝

The file will be created if it does not exist, and will be appended to if it does. If an error occurs while attempting to write the warning to the file, the warning will be written to stderr instead. so worst case you still get your warnings, king behavior honestly 👑

The file name may be an absolute path. If it is not, the default directory it will be written to is controlled by the --diagnostic-dir command-line option. ✨

✨ `--report-compact` ✨

Write reports in a compact format — single-line JSON — more easily consumable by log processing systems than the default multi-line format designed for human consumption. ngl it's giving "for the machines, not for me" but honestly? lowkey iconic for log pipelines 🌈

✨ `--report-dir=directory`, `--report-directory=directory` ✨

Location at which the report will be generated. 📁 that's literally it. pick a folder, get a report.

✨ `--report-exclude-env` ✨

When --report-exclude-env is passed, the diagnostic report generated will not contain the environmentVariables data. so if your env is a mess (no judgment, mine is too 😭) you can keep it out of the report 🫶

✨ `--report-exclude-network` ✨

Exclude header.networkInterfaces from the diagnostic report. By default this is not set and the network interfaces are included. so the network interfaces are in there unless you say otherwise, bestie 💜

✨ `--report-filename=filename` ✨

Name of the file to which the report will be written. 🎀

If the filename is set to 'stdout' or 'stderr', the report is written to the stdout or stderr of the process respectively. cute, right? no file needed, just yeet it at the terminal 💅

✨ `--report-on-fatalerror` ✨

Enables the report to be triggered on fatal errors (internal errors within the Node.js runtime such as out of memory) that lead to termination of the application. 💀

Useful to inspect various diagnostic data elements such as heap, stack, event loop state, resource consumption etc. to reason about the fatal error. think of it as the crime scene photos for when your app dies 🔍

✨ `--report-on-signal` ✨

Enables report to be generated upon receiving the specified (or predefined) signal to the running Node.js process. 📡

The signal to trigger the report is specified through --report-signal. so like, you poke it, it hands you a report. icon behavior ⭐

✨ `--report-signal=signal` ✨

Sets or resets the signal for report generation (not supported on Windows 🙈). Default signal is SIGUSR2. periodt.

✨ `--report-uncaught-exception` ✨

Enables report to be generated when the process exits due to an uncaught exception. 💥

Useful when inspecting the JavaScript stack in conjunction with native stack and other runtime environment data. so when your code goes "not me throwing an error" you get both stacks to look at 🫶

✨ `-r`, `--require module` ✨

Preload the specified module at startup. 🌅

Follows require()'s module resolution rules. module may be either a path to a file, or a node module name. 📦

Modules preloaded with --require will run before modules preloaded with --import. and like, they're preloaded into the main thread as well as any worker threads, forked processes, or clustered processes. everyone gets the preload, no one is left out 💖

✨ `--run` ✨

This runs a specified command from a package.json's "scripts" object. 🏃‍♀️

If a missing "command" is provided, it will list the available scripts. so like, node --run with no command is basically "show me the menu" 🍓

--run will traverse up to the root directory and finds a package.json file to run the command from. 🔍

--run prepends ./node_modules/.bin for each ancestor of the current directory, to the PATH in order to execute the binaries from different folders where multiple node_modules directories are present, if ancestor-folder/node_modules/.bin is a directory. 🛤️

--run executes the command in the directory containing the related package.json. For example, the following command will run the test script of the package.json in the current folder:

$ node --run test

You can also pass arguments to the command. Any argument after -- will be appended to the script:

$ node --run test -- --verbose

see? the -- is the little door 🚪 everything after it goes straight to the script. cute and useful, we love a double-duty queen 👑

✨ `--secure-heap-min=n` ✨

When using --secure-heap, the --secure-heap-min flag specifies the minimum allocation from the secure heap. 🎀

The minimum value is 2. The maximum value is the lesser of --secure-heap or 2147483647. The value given must be a power of two. ⚠️ no cap, it must be a power of two, don't try to be cute with 3.

✨ `--secure-heap=n` ✨

Initializes an OpenSSL secure heap of n bytes. 🔐

When initialized, the secure heap is used for selected types of allocations within OpenSSL during key generation and other operations. This is useful, for instance, to prevent sensitive information from leaking due to pointer overruns or underruns. honestly? protective queen behavior 💅

The secure heap is a fixed size and cannot be resized at runtime so, if used, it is important to select a large enough heap to cover all application uses. 🫶 (fr fr, you can't resize it later — pick generously.)

The heap size given must be a power of two. Any value less than 2 will disable the secure heap. The secure heap is disabled by default. The secure heap is not available on Windows. see CRYPTO_secure_malloc_init for more details. ✨

✨ `--snapshot-blob=path` ✨

When used with --build-snapshot, --snapshot-blob specifies the path where the generated snapshot blob is written to. If not specified, the generated blob is written to snapshot.blob in the current working directory. 📦

When used without --build-snapshot, --snapshot-blob specifies the path to the blob that is used to restore the application state. 🔄

When loading a snapshot, Node.js checks that:

The version, architecture, and platform of the running Node.js binary are exactly the same as that of the binary that generates the snapshot.
The V8 flags and CPU features are compatible with that of the binary that generates the snapshot.

If they don't match, Node.js refuses to load the snapshot and exits with status code 1. 💀 so like, no vibes-based loading. it checks, and it will absolutely say no.

✨ `--test` ✨

Starts the Node.js command line test runner. 🧪

This flag cannot be combined with --watch-path, --check, --eval, --interactive, or the inspector. 🙈

See the documentation on running tests from the command line for more details. 🎀

✨ `--test-concurrency` ✨

The maximum number of test files that the test runner CLI will execute concurrently. 🏃‍♀️🏃‍♀️🏃‍♀️

If --test-isolation is set to 'none', this flag is ignored and concurrency is one. Otherwise, concurrency defaults to os.availableParallelism() - 1. slay, it knows how many cores you have 👑

✨ `--test-coverage-branches=threshold` ✨

Require a minimum percent of covered branches. 🌿

If code coverage does not reach the threshold specified, the process will exit with code 1. so like, hit the bar or get the door 💅

✨ `--test-coverage-exclude` ✨

Excludes specific files from code coverage using a glob pattern, which can match both absolute and relative file paths. 🚫

This option may be specified multiple times to exclude multiple glob patterns. If both --test-coverage-exclude and --test-coverage-include are provided, files must meet both criteria to be included in the coverage report. 🫶

By default all the matching test files are excluded from the coverage report. Specifying this option will override the default behavior. so yeah, the default already skips test files — you're changing that by speaking up 🎀

✨ `--test-coverage-functions=threshold` ✨

Require a minimum percent of covered functions. 🔧

If code coverage does not reach the threshold specified, the process will exit with code 1. same energy as the branches one, just functions ✨

✨ `--test-coverage-include` ✨

Includes specific files in code coverage using a glob pattern, which can match both absolute and relative file paths. ✅

This option may be specified multiple times to include multiple glob patterns. If both --test-coverage-exclude and --test-coverage-include are provided, files must meet both criteria to be included in the coverage report. 💖

✨ `--test-coverage-include-all` ✨

Includes source files that were never loaded by the test run in the coverage report, where they are reported as having zero coverage. 😭 (brutal but honest)

Candidate files are searched for in the current working directory, and are subject to the same --test-coverage-include and --test-coverage-exclude filtering as the rest of the report. 🔍

✨ `--test-coverage-lines=threshold` ✨

Require a minimum percent of covered lines. 📏

If code coverage does not reach the threshold specified, the process will exit with code 1. hit the number or exit 1, that's the deal 🫶

✨ `--test-force-exit` ✨

Configures the test runner to exit the process once all known tests have finished executing even if the event loop would otherwise remain active. 🚪💨

like, tests are done, we're leaving, the event loop can stay if it wants but we're not waiting for it ✨

--test-global-setup=module — tells the test runner to load module before any of your tests run, so you can set up global state or fixtures 💖. See the docs on global setup and teardown for the full tea.
--test-isolation=mode — picks how isolated your tests are. When mode is 'process', every test file gets its own separate child process. When mode is 'none', all test files run in the same process as the test runner. Default is 'process' 🫶. Heads up: this flag is ignored if --test isn't present. See the test runner execution model section for more.
--test-name-pattern — a regular expression that makes the runner only execute tests whose name matches the pattern. See the docs on filtering tests by name ✨. And if you supply both --test-name-pattern and --test-skip-pattern, a test has to satisfy both requirements to actually get executed.
--test-only — makes the runner only execute top level tests that have the only option set. Lowkey you don't even need this flag when test isolation is disabled 💅.
--test-random-seed — sets the seed used to randomize test execution order. This applies to both test file execution order and the queued tests within each file 🔥. Passing this flag enables randomization implicitly, even without --test-randomize. The value must be an integer between 0 and 4294967295. Cannot be used with --watch or --test-rerun-failures.
--test-randomize — randomizes test execution order, for both test file execution order and the queued tests within each file. Great for catching tests that secretly rely on shared state or execution order 👀. The seed used for randomization gets printed in the test summary and can be reused with --test-random-seed. For detailed behavior and examples, see randomizing tests execution order. Cannot be used with --watch or --test-rerun-failures.
--test-reporter — which test reporter to use when running tests. See the docs on test reporters for more 💖.
--test-reporter-destination — the destination for the corresponding test reporter. See the docs on test reporters for more.
--test-rerun-failures — a path to a file that lets the test runner persist the state of the test suite between runs 💾. The runner uses this file to figure out which tests already succeeded or failed, so it can re-run just the failed ones without re-running the entire suite. It creates this file if it doesn't exist. See the docs on test reruns for more.
--test-shard — which test suite shard to execute, in the format <index>/<total>, where:
- index is a positive integer, the index of the divided parts.
- total is a positive integer, the total of the divided parts.

This command divides all test files into total equal parts and runs only the ones that happen to land in the index part 🎀. So to split your suite into three parts, you'd do:

node --test --test-shard=1/3
node --test --test-shard=2/3
node --test --test-shard=3/3

--test-skip-pattern — a regular expression that makes the runner skip tests whose name matches the pattern. See the docs on filtering tests by name ✨. If both --test-name-pattern and --test-skip-pattern are supplied, tests must satisfy both requirements in order to be executed.
--test-timeout — a number of milliseconds after which the test execution fails ⏰. If unspecified, subtests inherit this value from their parent. Default value is Infinity.
--test-update-snapshots — regenerates the snapshot files the test runner uses for snapshot testing 📸.
--throw-deprecation — throw errors for deprecations. No quiet warnings here, we're throwing hands 😤.
--title=title — sets process.title on startup.
--tls-cipher-list=list — specify an alternative default TLS cipher list. Requires Node.js to be built with crypto support (which is the default) 🔐.
--tls-keylog=file — logs TLS key material to a file. The key material is in NSS SSLKEYLOGFILE format and can be used by software (such as Wireshark) to decrypt the TLS traffic 👀.
--tls-max-v1.2 — sets tls.DEFAULT_MAX_VERSION to 'TLSv1.2'. Use it to disable support for TLSv1.3.
--tls-max-v1.3 — sets default tls.DEFAULT_MAX_VERSION to 'TLSv1.3'. Use it to enable support for TLSv1.3.
--tls-min-v1.0 — sets default tls.DEFAULT_MIN_VERSION to 'TLSv1'. Use it for compatibility with old TLS clients or servers 🧓.
--tls-min-v1.1 — sets default tls.DEFAULT_MIN_VERSION to 'TLSv1.1'. Also for compatibility with old TLS clients or servers.
--tls-min-v1.2 — sets default tls.DEFAULT_MIN_VERSION to 'TLSv1.2'. This is the default for 12.x and later, but the option is supported for compatibility with older Node.js versions.
--tls-min-v1.3 — sets default tls.DEFAULT_MIN_VERSION to 'TLSv1.3'. Use it to disable support for TLSv1.2, which is not as secure as TLSv1.3 💅.
--trace-deprecation — print stack traces for deprecations.
--trace-env — prints info about any access to environment variables done in the current Node.js instance to stderr, including:
- the environment variable reads that Node.js does internally,
- writes in the form of process.env.KEY = "SOME VALUE",
- reads in the form of process.env.KEY,
- definitions in the form of Object.defineProperty(process.env, 'KEY', {...}),
- queries in the form of Object.hasOwn(process.env, 'KEY'), process.env.hasOwnProperty('KEY') or 'KEY' in process.env,
- deletions in the form of delete process.env.KEY,
- enumerations in the form of ...process.env or Object.keys(process.env).

Only the names of the environment variables being accessed are printed — the values are not 🔒. To also print the stack trace of the access, use --trace-env-js-stack and/or --trace-env-native-stack.

--trace-env-js-stack — on top of what --trace-env does, this prints the JavaScript stack trace of the access 🌸.
--trace-env-native-stack — on top of what --trace-env does, this prints the native stack trace of the access.
--trace-event-categories — a comma separated list of categories that should be traced when trace event tracing is enabled using --trace-events-enabled.
--trace-event-file-pattern — template string specifying the filepath for the trace event data. It supports ${rotation} and ${pid} 🎀.
--trace-events-enabled — enables the collection of trace event tracing information.
--trace-exit — prints a stack trace whenever an environment is exited proactively, i.e. invoking process.exit().
--trace-require-module=mode — prints info about usage of Loading ECMAScript modules using require(). When mode is all, all usage is printed. When mode is no-node-modules, usage from the node_modules folder is excluded 🦋.
--trace-sigint — prints a stack trace on SIGINT.
--trace-sync-io — prints a stack trace whenever synchronous I/O is detected after the first turn of the event loop 👀.
--trace-tls — prints TLS packet trace information to stderr. Can be used to debug TLS connection problems 🔍.
--trace-uncaught — print stack traces for uncaught exceptions. Usually the stack trace associated with the creation of an Error is printed, whereas this makes Node.js also print the stack trace associated with throwing the value (which does not need to be an Error instance). Warning though: enabling this option may affect garbage collection behavior negatively 💀.
--trace-warnings — print stack traces for process warnings (including deprecations).
--track-heap-objects — track heap object allocations for heap snapshots.
--unhandled-rejections=mode — lets you change what happens when an unhandled rejection occurs 😭. Pick one of these modes:
- throw: emit unhandledRejection. If this hook is not set, raise the unhandled rejection as an uncaught exception. This is the default.
- strict: raise the unhandled rejection as an uncaught exception. If the exception is handled, unhandledRejection is emitted.
- warn: always trigger a warning, no matter if the unhandledRejection hook is set or not, but do not print the deprecation warning.
- warn-with-error-code: emit unhandledRejection. If this hook is not set, trigger a warning and set the process exit code to 1.
- none: silence all warnings 🤫.

If a rejection happens during the command line entry point's ES module static loading phase, it will always raise it as an uncaught exception.

--use-bundled-ca, --use-openssl-ca — use the bundled Mozilla CA store as supplied by the current Node.js version, or use OpenSSL's default CA store. The default store is selectable at build-time 🎀.

The bundled CA store, as supplied by Node.js, is a snapshot of the Mozilla CA store that is fixed at release time. It's identical on all supported platforms.

Using the OpenSSL store allows for external modifications of the store. For most Linux and BSD distributions, this store is maintained by the distribution maintainers and system administrators. The OpenSSL CA store location depends on the configuration of the OpenSSL library, but it can be altered at runtime using environment variables 🌈.

See SSL_CERT_DIR and SSL_CERT_FILE.

--use-env-proxy — okay so when this is enabled, Node.js parses the HTTP_PROXY, HTTPS_PROXY and NO_PROXY environment variables during startup, and routes requests through the specified proxy. Use this only with proxies that are trusted and authorized for the deployment. Proxy support is intended for reaching external networks through authorized proxy servers, for example when a firewall requires one. It is not for hiding traffic or evading network policy. See Built-in Proxy Support. This is equivalent to setting the NODE_USE_ENV_PROXY=1 environment variable. When both are set, --use-env-proxy takes precedence.
--use-largepages=mode — Re-map the Node.js static code to large memory pages at startup. If supported on the target system, this will cause the Node.js static code to be moved onto 2 MiB pages instead of 4 KiB pages. The following values are valid for mode:
- off: No mapping will be attempted. This is the default.
- on: If supported by the OS, mapping will be attempted. Failure to map will be ignored and a message will be printed to standard error.
- silent: If supported by the OS, mapping will be attempted. Failure to map will be ignored and will not be reported.
--use-system-ca — Node.js uses the trusted CA certificates present in the system store along with the --use-bundled-ca option and the NODE_EXTRA_CA_CERTS environment variable. On platforms other than Windows and macOS, this loads certificates from the directory and file trusted by OpenSSL, similar to --use-openssl-ca, with the difference being that it caches the certificates after first load. On Windows and macOS, the certificate trust policy is similar to Chromium's policy for locally trusted certificates, but with some differences: On macOS, the following settings are respected:
- Default and System Keychains.Bl -bullet
- Trust:.Bl -bullet
- Any certificate where the “When using this certificate” flag is set to “Always Trust” or
- Any certificate where the “Secure Sockets Layer (SSL)” flag is set to “Always Trust”.

The certificate must also be valid, with "X.509 Basic Policy" set to “Always Trust”.

On Windows, the following settings are respected:

Local Machine (accessed via certlm.msc).Bl -bullet
- Trust:.Bl -bullet
- Trusted Root Certification Authorities
- Trusted People
- Enterprise Trust -> Enterprise -> Trusted Root Certification Authorities
- Enterprise Trust -> Enterprise -> Trusted People
- Enterprise Trust -> Group Policy -> Trusted Root Certification Authorities
- Enterprise Trust -> Group Policy -> Trusted People
Current User (accessed via certmgr.msc).Bl -bullet
- Trust:.Bl -bullet
- Trusted Root Certification Authorities
- Enterprise Trust -> Group Policy -> Trusted Root Certification Authorities

On Windows and macOS, Node.js would check that the user settings for the trusted certificates do not forbid them for TLS server authentication before using them. Node.js currently does not support distrust/revocation of certificates from another source based on system settings. On other systems, Node.js loads certificates from the default certificate file (typically /etc/ssl/cert.pem) and default certificate directory (typically /etc/ssl/certs) that the version of OpenSSL that Node.js links to respects. This typically works with the convention on major Linux distributions and other Unix-like systems. If the overriding OpenSSL environment variables (typically SSL_CERT_FILE and SSL_CERT_DIR, depending on the configuration of the OpenSSL that Node.js links to) are set, the specified paths will be used to load certificates instead. These environment variables can be used as workarounds if the conventional paths used by the version of OpenSSL Node.js links to are not consistent with the system configuration that the users have for some reason.

--v8-options — Print V8 command-line options.
--v8-pool-size=num — Set V8's thread pool size which will be used to allocate background jobs. If set to 0 then Node.js will choose an appropriate size of the thread pool based on an estimate of the amount of parallelism. The amount of parallelism refers to the number of computations that can be carried out simultaneously in a given machine. In general, it's the same as the amount of CPUs, but it may diverge in environments such as VMs or containers.
--version — Print node's version.
--watch — Starts Node.js in watch mode. When in watch mode, changes in the watched files cause the Node.js process to restart. By default, watch mode will watch the entry point and any required or imported module. Use --watch-path to specify what paths to watch. This flag cannot be combined with --check, --eval, --interactive, or the REPL. Note: The --watch flag requires a file path as an argument and is incompatible with --run or inline script input, as --run takes precedence and ignores watch mode. If no file is provided, Node.js will exit with status code 9.

node --watch index.js

--watch-kill-signal=signal — Customizes the signal sent to the process on watch mode restarts.

node --watch --watch-kill-signal SIGINT test.js

--watch-path=path — Starts Node.js in watch mode and specifies what paths to watch. When in watch mode, changes in the watched paths cause the Node.js process to restart. This will turn off watching of required or imported modules, even when used in combination with --watch. This flag cannot be combined with --check, --eval, --interactive, --test, or the REPL. Note: Using --watch-path implicitly enables --watch, which requires a file path and is incompatible with --run, as --run takes precedence and ignores watch mode.

node --watch-path=./src --watch-path=./tests index.js

This option is only supported on macOS and Windows. An ERR_FEATURE_UNAVAILABLE_ON_PLATFORM exception will be thrown when the option is used on a platform that does not support it.

--watch-preserve-output — Disable the clearing of the console when watch mode restarts the process.

node --watch --watch-preserve-output test.js

--zero-fill-buffers — Automatically zero-fills all newly allocated Buffer instances.

🌈 ENVIRONMENT 🌈

FORCE_COLOR [1, 2, 3] — The FORCE_COLOR environment variable is used to enable ANSI colorized output. The value may be:
- 1, true, or the empty string '' indicate 16-color support,
- 2 to indicate 256-color support, or
- 3 to indicate 16 million-color support.

When FORCE_COLOR is used and set to a supported value, both the NO_COLOR, and NODE_DISABLE_COLORS environment variables are ignored. Any other value will result in colorized output being disabled.

NODE_COMPILE_CACHE dir — Enable the module compile cache for the Node.js instance. See the documentation of module compile cache for details.
NODE_COMPILE_CACHE_PORTABLE 1 — When set to 1, the module compile cache can be reused across different directory locations as long as the module layout relative to the cache directory remains the same, and by any user (the cache subdirectory is not suffixed with the creating user's uid).
NODE_COMPILE_CACHE_READONLY 1 — When set to 1, the module compile cache only reads existing entries from its directory: nothing is written to it and it is not created if missing.
NODE_DEBUG module[,…] — ','-separated list of core modules that should print debug information.
NODE_DEBUG_NATIVE module[,…] — ','-separated list of core C++ modules that should print debug information.
NODE_DISABLE_COLORS 1 — When set, colors will not be used in the REPL.
NODE_DISABLE_COMPILE_CACHE 1 — Disable the module compile cache for the Node.js instance. See the documentation of module compile cache for details.
NODE_EXTRA_CA_CERTS file — When set, the well known "root" CAs (like VeriSign) will be extended with the extra certificates in file. The file should consist of one or more trusted certificates in PEM format. A message will be emitted (once) with process.emitWarning() if the file is missing or malformed, but any errors are otherwise ignored. Neither the well known nor extra certificates are used when the ca options property is explicitly specified for a TLS or HTTPS client or server. This environment variable is ignored when node runs as setuid root or has Linux file capabilities set. The NODE_EXTRA_CA_CERTS environment variable is only read when the Node.js process is first launched. Changing the value at runtime using process.env.NODE_EXTRA_CA_CERTS has no effect on the current process.
NODE_ICU_DATA file — Data path for ICU (Intl object) data. Will extend linked-in data when compiled with small-icu support.
NODE_NO_WARNINGS 1 — When set to 1, process warnings are silenced.
NODE_OPTIONS options... — A space-separated list of command-line options. options... are interpreted before command-line options, so command-line options will override or compound after anything in options.... Node.js will exit with an error if an option that is not allowed in the environment is used, such as -p or a script file. If an option value contains a space, it can be escaped using double quotes:

NODE_OPTIONS='--require "./my path/file.js"'

A singleton flag passed as a command-line option will override the same flag passed into NODE_OPTIONS:

# The inspector will be available on port 5555
NODE_OPTIONS='--inspect=localhost:4444' node --inspect=localhost:5555

A flag that can be passed multiple times will be treated as if its NODE_OPTIONS instances were passed first, and then its command-line instances afterwards:

NODE_OPTIONS='--require "./a.js"' node --require "./b.js"
# is equivalent to:
node --require "./a.js" --require "./b.js"

Node.js options that are allowed are in the following list. If an option supports both --XX and --no-XX variants, they are both supported but only one is included in the list below.

--allow-addons
--allow-child-process
--allow-ffi
--allow-fs-read
--allow-fs-write
--allow-inspector
--allow-net
--allow-openssl-store
--allow-wasi
--allow-worker
--conditions, -C
--cpu-prof-dir
--cpu-prof-interval
--cpu-prof-name
--cpu-prof
--diagnostic-dir
--disable-proto

...and the allowlist keeps going, bestie. Here's the rest of the Node.js options you're allowed to tuck into NODE_OPTIONS — every single one, no skipping ✨

--disable-sigusr1
--disable-warning
--disable-wasm-trap-handler
--dns-result-order
--enable-fips
--enable-network-family-autoselection
--enable-source-maps
--entry-url
--experimental-abortcontroller
--experimental-addon-modules
--experimental-detect-module
--experimental-eventsource
--experimental-ffi
--experimental-import-meta-resolve
--experimental-import-text
--experimental-json-modules
--experimental-loader
--experimental-modules
--experimental-package-map
--experimental-print-required-tla
--experimental-quic
--experimental-require-module
--experimental-shadow-realm
--experimental-specifier-resolution
--experimental-stream-iter
--experimental-test-isolation
--experimental-top-level-await
--experimental-vfs
--experimental-vm-modules
--experimental-wasi-unstable-preview1
--force-context-aware
--force-fips
--force-node-api-uncaught-exceptions-policy
--frozen-intrinsics
--heap-prof-dir
--heap-prof-interval
--heap-prof-name
--heap-prof
--heapsnapshot-near-heap-limit
--heapsnapshot-signal
--http-parser
--icu-data-dir
--import
--input-type
--insecure-http-parser
--inspect-brk
--inspect-port, --debug-port
--inspect-publish-uid
--inspect-wait
--inspect
--localstorage-file
--max-http-header-size
--max-old-space-size-percentage
--network-family-autoselection-attempt-timeout
--no-addons
--no-async-context-frame
--no-deprecation
--no-experimental-global-navigator
--no-experimental-repl-await
--no-experimental-sqlite
--no-experimental-strip-types
--no-experimental-websocket
--no-experimental-webstorage
--no-extra-info-on-fatal-exception
--no-force-async-hooks-checks
--no-global-search-paths
--no-network-family-autoselection
--no-strip-types
--no-warnings
--no-webstorage
--node-memory-debug
--openssl-config
--openssl-legacy-provider
--openssl-shared-config
--pending-deprecation
--permission-audit
--permission
--preserve-symlinks-main
--preserve-symlinks
--prof-process
--redirect-warnings
--report-compact
--report-dir, --report-directory
--report-exclude-env
--report-exclude-network
--report-filename
--report-on-fatalerror
--report-on-signal
--report-signal
--report-uncaught-exception
--require-module
--require, -r
--secure-heap-min
--secure-heap
--snapshot-blob
--test-coverage-branches
--test-coverage-exclude
--test-coverage-functions
--test-coverage-include-all
--test-coverage-include
--test-coverage-lines
--test-global-setup
--test-isolation
--test-name-pattern
--test-only
--test-random-seed
--test-randomize
--test-reporter-destination
--test-reporter
--test-rerun-failures
--test-shard
--test-skip-pattern
--throw-deprecation
--title
--tls-cipher-list
--tls-keylog
--tls-max-v1.2
--tls-max-v1.3
--tls-min-v1.0
--tls-min-v1.1
--tls-min-v1.2
--tls-min-v1.3
--trace-deprecation
--trace-env-js-stack
--trace-env-native-stack
--trace-env
--trace-event-categories
--trace-event-file-pattern
--trace-events-enabled
--trace-exit
--trace-require-module
--trace-sigint
--trace-sync-io
--trace-tls
--trace-uncaught
--trace-warnings
--track-heap-objects
--unhandled-rejections
--use-bundled-ca
--use-env-proxy
--use-largepages
--use-openssl-ca
--use-system-ca
--v8-pool-size
--watch-kill-signal
--watch-path
--watch-preserve-output
--watch
--zero-fill-buffers

V8 options that are allowed are:

--abort-on-uncaught-exception
--disallow-code-generation-from-strings
--enable-etw-stack-walking
--expose-gc
--interpreted-frames-native-stack
--jitless
--max-heap-size
--max-old-space-size
--max-semi-space-size
--perf-basic-prof-only-functions
--perf-basic-prof
--perf-prof-unwinding-info
--perf-prof
--stack-trace-limit

🦋 platform check, bestie: --perf-basic-prof-only-functions, --perf-basic-prof, --perf-prof-unwinding-info, and --perf-prof are only available on Linux. And --enable-etw-stack-walking is only available on Windows. No cap.

`NODE_PATH` path[:…]

A ':'-separated list of directories that get prefixed onto the module search path. On Windows it's a ';'-separated list instead — different separator, same slay 🌸

`NODE_PENDING_DEPRECATION` `1`

Set it to 1 and boom, you get pending deprecation warnings emitted 💅 Pending deprecations are basically identical to a runtime deprecation, except — and this is the whole point — they're turned off by default and won't be emitted unless you either pass the --pending-deprecation command-line flag or set NODE_PENDING_DEPRECATION=1. So it's like a selective "early warning" system developers can use to catch deprecated API usage before it bites. Obsessed with a heads-up, honestly.

`NODE_PENDING_PIPE_INSTANCES` instances

Sets how many pending pipe instance handles you get while the pipe server is sitting there waiting for connections. Windows only, queen — this setting doesn't apply anywhere else.

`NODE_PRESERVE_SYMLINKS` `1`

Set to 1 and the module loader is instructed to preserve symbolic links when it resolves and caches modules 🎀

`NODE_REDIRECT_WARNINGS` file

When it's set, process warnings get emitted to the given file instead of being printed to stderr. The file gets created if it doesn't exist, and appended to if it does. And if something goes wrong while trying to write the warning to the file? The warning goes to stderr instead — no lost warnings on my watch 😭 This is equivalent to using the --redirect-warnings=file command-line flag.

`NODE_REPL_EXTERNAL_MODULE` file

Path to a Node.js module that gets loaded in place of the built-in REPL. Override this value to an empty string ('') and you'll get the built-in REPL back. Iconic little toggle, fr fr.

`NODE_REPL_HISTORY` file

Path to the file used to store the persistent REPL history 📜 Default path is ~/.node_repl_history, and this variable overrides it. Set the value to an empty string ('' or ' ') and persistent REPL history is disabled entirely.

`NODE_SKIP_PLATFORM_CHECK` value

If value equals '1', the check for a supported platform gets skipped during Node.js startup.

💀 real talk: Node.js might not execute correctly if you do this. Any issues you hit on unsupported platforms will not be fixed. You've been warned, bestie.

`NODE_TEST_CONTEXT` value

If value equals 'child', test reporter options get overridden and test output is sent to stdout in the TAP format. If you pass any other value, Node.js makes no guarantees about which reporter format gets used or whether it's even stable 🙈

`NODE_TLS_REJECT_UNAUTHORIZED` value

If value equals '0', certificate validation is disabled for TLS connections.

🚨 This makes TLS — and HTTPS by extension — insecure. The use of this environment variable is strongly discouraged. Like, genuinely. Please don't just leave this in prod, I'm begging 😭

`NODE_USE_ENV_PROXY` `1`

When enabled, Node.js parses the HTTP_PROXY, HTTPS_PROXY and NO_PROXY environment variables during startup, and routes requests through the specified proxy 🧚

Use this only with proxies that are trusted and authorized for the deployment. Proxy support is intended for reaching external networks through authorized proxy servers — for example when a firewall requires one. It is not for hiding traffic or evading network policy. See Built-in Proxy Support. This can also be enabled using the --use-env-proxy command-line flag, and when both are set, --use-env-proxy takes precedence ✨

`NODE_USE_SYSTEM_CA` `1`

Node.js uses the trusted CA certificates present in the system store, along with the --use-bundled-ca option and the NODE_EXTRA_CA_CERTS environment variable 🔐 This can also be enabled using the --use-system-ca command-line flag, and when both are set, --use-system-ca takes precedence. Crown behavior only 👑

🌸 `NODE_V8_COVERAGE` dir

okay so when this one's set, Node.js starts outputting V8 JavaScript code coverage and Source Map data into the directory you passed as the argument — the coverage info gets written as JSON to files with a coverage prefix. 💖 The bestie behaviour here is that NODE_V8_COVERAGE automatically propagates to subprocesses, which makes instrumenting apps that call the child_process.spawn() family of functions so much easier. And yes, you can set NODE_V8_COVERAGE to an empty string if you want to prevent that propagation — little off switch, love that for you. 🎀

🌈 `NO_COLOR` <any>

NO_COLOR is literally just an alias for NODE_DISABLE_COLORS. The value of the environment variable is arbitrary — put whatever you want in it, it does not care. 💅

🦋 `OPENSSL_CONF` file

Loads an OpenSSL configuration file on startup, periodt. The file can be used as part of a FIPS mode configuration. 🧚

If the variable is set to an empty value, Node.js starts without loading any OpenSSL configuration file. This is a way past a default configuration file that exists but cannot be read — for example when /etc/ssl is not accessible to the user Node.js runs as, which is otherwise fatal at startup. 😭 No configuration is applied in that case, including any FIPS mode setup the file would have performed.

Heads up bestie: if the --openssl-config command-line option is used, the environment variable is ignored, and an empty value has no effect. 🫶

🔥 `SSL_CERT_DIR` dir

If --use-openssl-ca is enabled, or if --use-system-ca is enabled on platforms other than macOS and Windows, this overrides and sets OpenSSL's directory containing trusted certificates. 🎀

Be aware that unless the child environment is explicitly set, this environment variable will be inherited by any child processes, and if they use OpenSSL, it may cause them to trust the same CAs as node. 👀

⭐ `SSL_CERT_FILE` file

Same energy, different target: if --use-openssl-ca is enabled, or if --use-system-ca is enabled on platforms other than macOS and Windows, this overrides and sets OpenSSL's file containing trusted certificates. 💜

Again, fr fr: unless the child environment is explicitly set, this environment variable will be inherited by any child processes, and if they use OpenSSL, it may cause them to trust the same CAs as node. 🙈

🕰️ `TZ`

The TZ environment variable is used to specify the timezone configuration. Node.js does not support all of the various ways that TZ is handled in other environments, but it does support basic timezone IDs (such as 'Etc/UTC', 'Europe/Paris', or 'America/New_York'). 🌍

It may support a few other abbreviations or aliases, but these are strongly discouraged and not guaranteed — so like, don't come for me if your weird custom abbreviation doesn't hit. 💀

$ TZ=Europe/Dublin node -pe "new Date().toString()"
Wed May 12 2021 20:30:48 GMT+0100 (Irish Standard Time)

🧵 `UV_THREADPOOL_SIZE` size

Sets the number of threads used in libuv's threadpool to size threads. ✨

Asynchronous system APIs are used by Node.js whenever possible, but where they do not exist, libuv's threadpool is used to create asynchronous node APIs based on synchronous system APIs. The Node.js APIs that use the threadpool are:

all fs APIs, other than the file watcher APIs and those that are explicitly synchronous
asynchronous crypto APIs such as crypto.pbkdf2(), crypto.scrypt(), crypto.randomBytes(), crypto.randomFill(), crypto.generateKeyPair()
dns.lookup()
all zlib APIs, other than those that are explicitly synchronous

Because libuv's threadpool has a fixed size, it means that if for whatever reason any of these APIs takes a long time, other (seemingly unrelated) APIs that run in libuv's threadpool will experience degraded performance. 😭 In order to mitigate this issue, one potential solution is to increase the size of libuv's threadpool by setting the 'UV_THREADPOOL_SIZE' environment variable to a value greater than 4 (its current default value).

But listen — setting this from inside the process using process.env.UV_THREADPOOL_SIZE=size is not guaranteed to work, as the threadpool would have been created as part of the runtime initialisation much before user code is run. 💅 For more information, see the libuv threadpool documentation.

🐛 BUGS

Bugs are tracked in GitHub Issues: https://github.com/nodejs/node/issues — go snitch, bestie, they want to know. 🔍

©️ COPYRIGHT

Node.js also includes external libraries that are available under a variety of licenses. See https://github.com/nodejs/node/blob/HEAD/LICENSE for the full license text.

👀 SEE ALSO

Website: https://nodejs.org/
Documentation: https://nodejs.org/api/
GitHub repository and issue tracker: https://github.com/nodejs/node

and that's the whole page, bestie — you made it to the end of NODE(1) 🎉🫶 this little edition is stamped $Mdocdate$ and filed under NODE(1), so go be the main character of your own shell and slay responsibly 💅✨

📦 where this page comes from

centos-stream 10: nodejs26 1:26.8.2-1.el10 · Apache-2.0 AND Artistic-2.0 AND BSD-2-Clause AND BSD-3-Clause AND BlueOak-1.0.0 AND CC-BY-3.0 AND CC0-1.0 AND ISC AND MIT
💖 girlified by deepseek-ai/DeepSeek-V4.1-Flash-1017 on 2026-11-04: a language model's rewrite of the original, under its terms

NODE-26(1)

💖 NODE-26(1) 💖

✨ NAME ✨

🌸 SYNOPSIS 🌸

🦋 DESCRIPTION 🦋

🌈 OPTIONS 🌈

✨ --preserve-symlinks-main ✨

✨ -p, --print script ✨

✨ --prof ✨

✨ --prof-process ✨

✨ --redirect-warnings=file ✨

✨ --report-compact ✨

✨ --report-dir=directory, --report-directory=directory ✨

✨ --report-exclude-env ✨

✨ --report-exclude-network ✨

✨ --report-filename=filename ✨

✨ --report-on-fatalerror ✨

✨ --report-on-signal ✨

✨ --report-signal=signal ✨

✨ --report-uncaught-exception ✨

✨ -r, --require module ✨

✨ --run ✨

✨ --secure-heap-min=n ✨

✨ --secure-heap=n ✨

✨ --snapshot-blob=path ✨

✨ --test ✨

✨ --test-concurrency ✨

✨ --test-coverage-branches=threshold ✨

✨ --test-coverage-exclude ✨

✨ --test-coverage-functions=threshold ✨

✨ --test-coverage-include ✨

✨ --test-coverage-include-all ✨

✨ --test-coverage-lines=threshold ✨

✨ --test-force-exit ✨