node man page

node — server-side JavaScript runtime

Examples (TL;DR)

Synopsis

node[options] [v8-options] [-e string | script.js | -] [--] [arguments ...]
nodeinspect [-e string | script.js | - | <host>:<port>] ...
node[--v8-options]

Description

Node.js is a set of libraries for JavaScript which allows it to be used outside of the browser. It is primarily focused on creating simple, easy-to-build network clients and servers.

Execute node without arguments to start a REPL.

Options

-

Alias for stdin, analogous to the use of - in other command-line utilities. The executed script is read from stdin, and remaining arguments are passed to the script.

--

Indicate the end of command-line options. Pass the rest of the arguments to the script.

If no script filename or eval/print script is supplied prior to this, then the next argument will be used as a script filename.

--abort-on-uncaught-exception

Aborting instead of exiting causes a core file to be generated for analysis.

--completion-bash

Print source-able bash completion script for Node.js.

--cpu-prof

Start the V8 CPU profiler on start up, and write the CPU profile to disk before exit. If --cpu-prof-dir is not specified, the profile will be written to the current working directory with a generated file name.

--cpu-prof-dir

The directory where the CPU profiles generated by --cpu-prof will be placed.

--cpu-prof-interval

The sampling interval in microseconds for the CPU profiles generated by --cpu-prof. The default is 1000.

--cpu-prof-name

File name of the V8 CPU profile generated with --cpu-prof

--enable-fips

Enable FIPS-compliant crypto at startup. Requires Node.js to be built with ./configure --openssl-fips.

--es-module-specifier-resolution

Select extension resolution algorithm for ES Modules; either 'explicit' (default) or 'node'

--experimental-modules

Enable experimental ES module support and caching modules.

--experimental-policy

Use the specified file as a security policy.

--experimental-repl-await

Enable experimental top-level await keyword support in REPL.

--experimental-report

Enable experimental diagnostic report feature.

--experimental-vm-modules

Enable experimental ES module support in VM module.

--experimental-wasm-modules

Enable experimental WebAssembly module support.

--force-fips

Force FIPS-compliant crypto on startup (Cannot be disabled from script code). Same requirements as --enable-fips.

--frozen-intrinsics

Enable experimental frozen intrinsics support.

--heapsnapshot-signal=signal

Generate heap snapshot on specified signal.

--heap-prof

Start the V8 heap profiler on start up, and write the heap profile to disk before exit. If --heap-prof-dir is not specified, the profile will be written to the current working directory with a generated file name.

--heap-prof-dir

The directory where the heap profiles generated by --heap-prof will be placed.

--heap-prof-interval

The average sampling interval in bytes for the heap profiles generated by --heap-prof. The default is 512 * 1024.

--heap-prof-name

File name of the V8 heap profile generated with --heap-prof

--http-parser=library

Chooses an HTTP parser library. Available values are llhttp or legacy.

--http-server-default-timeout=milliseconds

Overrides the default value for server socket timeout.

--icu-data-dir=file

Specify ICU data load path. Overrides NODE_ICU_DATA.

--input-type=type

Set the module resolution type for input via --eval, --print or STDIN.

--inspect-brk=[host:]port

Activate inspector on host:port and break at start of user script.

--inspect-port=[host:]port

Set the host:port to be used when the inspector is activated.

--inspect=[host:]port

Activate inspector on host:port. Default is 127.0.0.1:9229.

V8 Inspector integration allows attaching Chrome DevTools and IDEs to Node.js instances for debugging and profiling. It uses the Chrome DevTools Protocol.

--loader=file

Specify the file as a custom loader, to load --experimental-modules.

--max-http-header-size=size

Specify the maximum size of HTTP headers in bytes. Defaults to 8KB.

--napi-modules

This option is a no-op. It is kept for compatibility.

--no-deprecation

Silence deprecation warnings.

--no-force-async-hooks-checks

Disable runtime checks for `async_hooks`. These will still be enabled dynamically when `async_hooks` is enabled.

--no-warnings

Silence all process warnings (including deprecations).

--openssl-config=file

Load an OpenSSL configuration file on startup. Among other uses, this can be used to enable FIPS-compliant crypto if Node.js is built with ./configure --openssl-fips.

--pending-deprecation

Emit pending deprecation warnings.

--policy-integrity=sri

Instructs Node.js to error prior to running any code if the policy does not have the specified integrity. It expects a Subresource Integrity string as a parameter.

--preserve-symlinks

Instructs the module loader to preserve symbolic links when resolving and caching modules other than the main module.

--preserve-symlinks-main

Instructs the module loader to preserve symbolic links when resolving and caching the main module.

--prof

Generate V8 profiler output.

--prof-process

Process V8 profiler output generated using the V8 option --prof.

--redirect-warnings=file

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

--report-directory

Location at which the diagnostic report will be generated.

--report-filename

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

--report-on-fatalerror

Enables the diagnostic report to be triggered on fatal errors (internal errors within the Node.js runtime such as out of memory) that leads to termination of the application, if --experimental-report is enabled. Useful to inspect various diagnostic data elements such as heap, stack, event loop state, resource consumption etc. to reason about the fatal error.

--report-on-signal

Enables diagnostic report to be generated upon receiving the specified (or predefined) signal to the running Node.js process, if --experimental-report is enabled. Default signal is SIGUSR2.

--report-signal

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

--report-uncaught-exception

Enables diagnostic report to be generated on un-caught exceptions, if --experimental-report is enabled. Useful when inspecting JavaScript stack in conjunction with native stack and other runtime environment data.

--throw-deprecation

Throw errors for deprecations.

--title=title

Specify process.title on startup.

--tls-cipher-list=list

Specify an alternative default TLS cipher list. Requires Node.js to be built with crypto support. (Default)

--tls-max-v1.2

Set default maxVersion to 'TLSv1.2'. Use to disable support for TLSv1.3.

--tls-max-v1.3

Set default maxVersion to 'TLSv1.3'. Use to enable support for TLSv1.3.

--tls-min-v1.0

Set default minVersion to 'TLSv1'. Use for compatibility with old TLS clients or servers.

--tls-min-v1.1

Set default minVersion to 'TLSv1.1'. Use for compatibility with old TLS clients or servers.

--tls-min-v1.2

Set default minVersion 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

Set default minVersion to 'TLSv1.3'. Use to disable support for TLSv1.2 in favour of TLSv1.3, which is more secure.

--trace-deprecation

Print stack traces for deprecations.

--trace-event-categories 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 pattern

Template string specifying the filepath for the trace event data, it supports ${rotation} and ${pid}.

--trace-events-enabled

Enable the collection of trace event tracing information.

--trace-sync-io

Print 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.

--trace-warnings

Print stack traces for process warnings (including deprecations).

--track-heap-objects

Track heap object allocations for heap snapshots.

---unhandled-rejections=mode

Define the behavior for unhandled rejections. Can be one of `strict` (raise an error), `warn` (enforce warnings) or `none` (silence warnings).

--use-bundled-ca, --use-openssl-ca

Use bundled Mozilla CA store as supplied by 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 Mozilla CA store that is fixed at release time. It is identical on all supported platforms.

Using 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. OpenSSL CA store location is dependent on configuration of the OpenSSL library but this can be altered at runtime using environment variables.

See SSL_CERT_DIR and SSL_CERT_FILE.

--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 V8 will choose an appropriate size of the thread pool based on the number of online processors. If the value provided is larger than V8's maximum, then the largest value will be chosen.

--zero-fill-buffers

Automatically zero-fills all newly allocated Buffer and SlowBuffer instances.

-c, --check

Check the script's syntax without executing it. Exits with an error code if script is invalid.

-e, --eval string

Evaluate string as JavaScript.

-h, --help

Print command-line options. The output of this option is less detailed than this document.

-i, --interactive

Open the REPL even if stdin does not appear to be a terminal.

-p, --print string

Identical to -e, but prints the result.

-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.js module name.

-v, --version

Print node's version.

Environment

NODE_DEBUG modules...

Comma-separated list of core modules that should print debug information.

NODE_DEBUG_NATIVE modules...

Comma-separated list of C++ core modules that should print debug information.

NODE_DISABLE_COLORS

When set to 1, colors will not be used in the REPL.

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.

If file is missing or misformatted, a message will be emitted once using process.emitWarning(), but any errors are otherwise ignored.

This environment variable is ignored when `node` runs as setuid root or has Linux file capabilities set.

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

When set to 1, process warnings are silenced.

NODE_OPTIONS options...

A space-separated list of command-line options, which are interpreted as if they had been specified on the command-line before the actual command (so they can be overridden). Node.js will exit with an error if an option that is not allowed in the environment is used, such as --print or a script file.

NODE_PATH directories...

A colon-separated list of directories prefixed to the module search path.

NODE_PENDING_DEPRECATION

When set to 1, emit pending deprecation warnings.

NODE_PRESERVE_SYMLINKS

When set to 1, the module loader preserves symbolic links when resolving and caching modules.

NODE_REDIRECT_WARNINGS file

Write process warnings to the given file instead of printing to stderr. Equivalent to passing --redirect-warnings file on command-line.

NODE_REPL_HISTORY file

Path to the file used to store persistent REPL history. The default path is ~/.node_repl_history, which is overridden by this variable. Setting the value to an empty string ("" or " ") will disable persistent REPL history.

NODE_TLS_REJECT_UNAUTHORIZED

When set to 0, TLS certificate validation is disabled.

NODE_V8_COVERAGE dir

When set, Node.js writes JavaScript code coverage information to dir.

OPENSSL_CONF file

Load an OpenSSL configuration file on startup. Among other uses, this can be used to enable FIPS-compliant crypto if Node.js is built with ./configure --openssl-fips.

If the --openssl-config command-line option is used, this environment variable is ignored.

SSL_CERT_DIR dir

If --use-openssl-ca is enabled, this overrides and sets OpenSSL's directory containing trusted certificates.

SSL_CERT_FILE file

If --use-openssl-ca is enabled, this overrides and sets OpenSSL's file containing trusted certificates.

UV_THREADPOOL_SIZE size

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

Bugs

Bugs are tracked in GitHub Issues: https://github.com/nodejs/node/issues

See Also

Website: https://nodejs.org/

Documentation: https://nodejs.org/api/

GitHub repository & Issue Tracker: https://github.com/nodejs/node

IRC (general questions): chat.freenode.net #node.js (unofficial)

IRC (Node.js core development): chat.freenode.net #node-dev

Authors

Written and maintained by 1000+ contributors: https://github.com/nodejs/node/blob/master/AUTHORS

Referenced By

nodeunit(1).

2018