.Dd 2018

.Nm node

.Nd server-side JavaScript runtime

.Nm node

.Op Ar options

.Op Ar v8-options

.Op Fl e Ar string | Ar script.js | Fl

.Op Fl -

.Op Ar arguments ...

.Nm node

.Cm inspect

.Op Fl e Ar string | Ar script.js | Fl | Ar <host>:<port>

.Ar ...

.Nm node

.Op Fl -v8-options

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.

.Pp

Execute

.Nm

without arguments to start a REPL.

.Bl -tag -width 6n

.It Sy -

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.

.It Fl -

Indicate the end of command-line options.

Pass the rest of the arguments to the script.

.Pp

If no script filename or eval/print script is supplied prior to this, then

the next argument will be used as a script filename.

.It Fl -abort-on-uncaught-exception

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

.It Fl -completion-bash

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

.It Fl C , Fl -conditions Ar string

Use custom conditional exports conditions.

.Ar string

.It Fl -cpu-prof

Start the V8 CPU profiler on start up, and write the CPU profile to disk

before exit. If

.Fl -cpu-prof-dir

is not specified, the profile will be written to the current working directory

with a generated file name.

.It Fl -cpu-prof-dir

The directory where the CPU profiles generated by

.Fl -cpu-prof

will be placed.

The default value is controlled by the

.Fl -diagnostic-dir .

command-line option.

.It Fl -cpu-prof-interval

The sampling interval in microseconds for the CPU profiles generated by

.Fl -cpu-prof .

The default is

.Sy 1000 .

.It Fl -cpu-prof-name

File name of the V8 CPU profile generated with

.Fl -cpu-prof .

.It Fl -diagnostic-dir

Set the directory for all diagnostic output files.

Default is current working directory.

Set the directory to which all diagnostic output files will be written to.

Defaults to current working directory.

Affects the default output directory of:

.Fl -cpu-prof-dir .

.Fl -heap-prof-dir .

.Fl -redirect-warnings .

.It Fl -disable-proto Ns = Ns Ar mode

Disable the `Object.prototype.__proto__` property. If

.Ar mode

is `delete`, the property will be removed entirely. If

.Ar mode

is `throw`, accesses to the property will throw an exception with the code

`ERR_PROTO_ACCESS`.

.It Fl -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

`vm` module.

.It Fl -enable-fips

Enable FIPS-compliant crypto at startup.

Requires Node.js to be built with

.Sy ./configure --openssl-fips .

.It Fl -enable-source-maps

Enable Source Map V3 support for stack traces.

.It Fl -experimental-import-meta-resolve

Enable experimental ES modules support for import.meta.resolve().

.It Fl -experimental-json-modules

Enable experimental JSON interop support for the ES Module loader.

.It Fl -experimental-loader Ns = Ns Ar module

Specify the

.Ar module

to use as a custom module loader.

.It Fl -experimental-policy

Use the specified file as a security policy.

.It Fl -no-experimental-repl-await

Disable top-level await keyword support in REPL.

.It Fl -experimental-specifier-resolution

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

.It Fl -experimental-vm-modules

Enable experimental ES module support in VM module.

.It Fl -experimental-wasi-unstable-preview1

Enable experimental WebAssembly System Interface support.

.It Fl -experimental-wasm-modules

Enable experimental WebAssembly module support.

.It Fl -force-context-aware

Disable loading native addons that are not context-aware.

.It Fl -force-fips

Force FIPS-compliant crypto on startup

(Cannot be disabled from script code).

Same requirements as

.Fl -enable-fips .

.It Fl -frozen-intrinsics

Enable experimental frozen intrinsics support.

.It Fl -heapsnapshot-near-heap-limit Ns = Ns Ar max_count

Generate heap snapshot when the V8 heap usage is approaching the heap limit.

No more than the specified number of snapshots will be generated.

.It Fl -heapsnapshot-signal Ns = Ns Ar signal

Generate heap snapshot on specified signal.

.It Fl -heap-prof

Start the V8 heap profiler on start up, and write the heap profile to disk

before exit. If

.Fl -heap-prof-dir

is not specified, the profile will be written to the current working directory

with a generated file name.

.It Fl -heap-prof-dir

The directory where the heap profiles generated by

.Fl -heap-prof

will be placed.

The default value is controlled by the

.Fl -diagnostic-dir .

command-line option.

.It Fl -heap-prof-interval

The average sampling interval in bytes for the heap profiles generated by

.Fl -heap-prof .

The default is

.Sy 512 * 1024 .

.It Fl -heap-prof-name

File name of the V8 heap profile generated with

.Fl -heap-prof .

.It Fl -icu-data-dir Ns = Ns Ar file

Specify ICU data load path.

Overrides

.Ev NODE_ICU_DATA .

.It Fl -input-type Ns = Ns Ar type

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

.It Fl -inspect-brk Ns = Ns Ar [host:]port

Activate inspector on

.Ar host:port

and break at start of user script.

.It Fl -inspect-port Ns = Ns Ar [host:]port

Set the

.Ar host:port

to be used when the inspector is activated.

.It Fl -inspect-publish-uid=stderr,http

Specify how the inspector WebSocket URL is exposed.

Valid values are

.Sy stderr

and

.Sy http .

Default is

.Sy stderr,http .

.It Fl -inspect Ns = Ns Ar [host:]port

Activate inspector on

.Ar host:port .

Default is

.Sy 127.0.0.1:9229 .

.Pp

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

It uses the Chrome DevTools Protocol.

.It Fl -insecure-http-parser

Use an insecure HTTP parser that accepts invalid HTTP headers. This may allow

interoperability with non-conformant HTTP implementations. It may also allow

request smuggling and other HTTP attacks that rely on invalid headers being

accepted. Avoid using this option.

.It Fl -jitless

Disable 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.

.Pp

This flag is inherited from V8 and is subject to change upstream. It may

disappear in a non-semver-major release.

.It Fl -max-http-header-size Ns = Ns Ar size

Specify the maximum size of HTTP headers in bytes. Defaults to 16 KB.

.It Fl -napi-modules

This option is a no-op.

It is kept for compatibility.

.It Fl -no-deprecation

Silence deprecation warnings.

.It Fl -no-extra-info-on-fatal-exception

Hide extra information on fatal exception that causes exit.

.It Fl -no-force-async-hooks-checks

Disable runtime checks for `async_hooks`.

These will still be enabled dynamically when `async_hooks` is enabled.

.It Fl -no-addons

Disable the `node-addons` exports condition as well as disable loading native

addons. When `--no-addons` is specified, calling `process.dlopen` or requiring

a native C++ addon will fail and throw an exception.

.It Fl -no-global-search-paths

Do not search modules from global paths.

.It Fl -no-warnings

Silence all process warnings (including deprecations).

.It Fl -node-memory-debug

Enable extra debug checks for memory leaks in Node.js internals. This is

usually only useful for developers debugging Node.js itself.

.It Fl -openssl-config Ns = Ns Ar 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

.Sy ./configure --openssl-fips .

.It Fl -pending-deprecation

Emit pending deprecation warnings.

.It Fl -policy-integrity Ns = Ns Ar 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.

.It Fl -preserve-symlinks

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

.It Fl -preserve-symlinks-main

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

.It Fl -prof

Generate V8 profiler output.

.It Fl -prof-process

Process V8 profiler output generated using the V8 option

.Fl -prof .

.It Fl -redirect-warnings Ns = Ns Ar file

Write process warnings to the given

.Ar file

instead of printing to stderr.

.It Fl -report-compact

Write

.Sy diagnostic reports

in a compact format, single-line JSON.

.It Fl -report-dir Fl -report-directory

Location at which the

.Sy diagnostic report

will be generated.

The `file` name may be an absolute path. If it is not, the default directory it will

be written to is controlled by the

.Fl -diagnostic-dir .

command-line option.

.It Fl -report-filename

Name of the file to which the

.Sy diagnostic report

will be written.

.It Fl -report-on-fatalerror

Enables the

.Sy 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. Useful to

inspect various diagnostic data elements such as heap, stack, event loop state,

resource consumption etc. to reason about the fatal error.

.It Fl -report-on-signal

Enables

.Sy diagnostic report

to be generated upon receiving the specified (or predefined) signal to the

running Node.js process. Default signal is SIGUSR2.

.It Fl -report-signal

Sets or resets the signal for

.Sy diagnostic report

generation (not supported on Windows). Default signal is SIGUSR2.

.It Fl -report-uncaught-exception

Enables

.Sy diagnostic report

to be generated on un-caught exceptions. Useful when inspecting JavaScript

stack in conjunction with native stack and other runtime environment data.

.It Fl -secure-heap Ns = Ns Ar n

Specify the size of the OpenSSL secure heap. Any value less than 2 disables

the secure heap. The default is 0. The value must be a power of two.

.It Fl -secure-heap-min Ns = Ns Ar n

Specify the minimum allocation from the OpenSSL secure heap. The default is 2. The value must be a power of two.

.It Fl -throw-deprecation

Throw errors for deprecations.

.It Fl -title Ns = Ns Ar title

Specify process.title on startup.

.It Fl -tls-cipher-list Ns = Ns Ar list

Specify an alternative default TLS cipher list.

Requires Node.js to be built with crypto support. (Default)

.It Fl -tls-keylog Ns = Ns Ar file

Log 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.

.It Fl -tls-max-v1.2

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

.It Fl -tls-max-v1.3

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

.It Fl -tls-min-v1.0

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

or servers.

.It Fl -tls-min-v1.1

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

or servers.

.It Fl -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.

.It Fl -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.

.It Fl -trace-atomics-wait

Print short summaries of calls to

.Sy Atomics.wait() .

.It Fl -trace-deprecation

Print stack traces for deprecations.

.It Fl -trace-event-categories Ar categories

A comma-separated list of categories that should be traced when trace event tracing is enabled using

.Fl -trace-events-enabled .

.It Fl -trace-event-file-pattern Ar pattern

Template string specifying the filepath for the trace event data, it

supports

.Sy ${rotation}

and

.Sy ${pid} .

.It Fl -trace-events-enabled

Enable the collection of trace event tracing information.

.It Fl -trace-exit

Prints a stack trace whenever an environment is exited proactively,

i.e. invoking `process.exit()`.

.It Fl -trace-sigint

Prints a stack trace on SIGINT.

.It Fl -trace-sync-io

Print a stack trace whenever synchronous I/O is detected after the first turn of the event loop.

.It Fl -trace-tls

Prints TLS packet trace information to stderr.

.It Fl -trace-uncaught

Print stack traces for uncaught exceptions; usually, the stack trace associated

with the creation of an

.Sy 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

.Sy Error

instance).

.Pp

Enabling this option may affect garbage collection behavior negatively.

.It Fl -trace-warnings

Print stack traces for process warnings (including deprecations).

.It Fl -track-heap-objects

Track heap object allocations for heap snapshots.

.It Fl -unhandled-rejections=mode

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

.It Fl -use-bundled-ca , Fl -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.

.Pp

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.

.Pp

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.

.Pp

See

.Ev SSL_CERT_DIR

and

.Ev SSL_CERT_FILE .

.It Fl -use-largepages Ns = Ns Ar 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.

.Pp

.Ar mode

must have one of the following values:

`off` (the default value, meaning do not map), `on` (map and ignore failure,

reporting it to stderr), or `silent` (map and silently ignore failure).

.It Fl -v8-options

Print V8 command-line options.

.It Fl -v8-pool-size Ns = Ns Ar 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.

.It Fl -zero-fill-buffers

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

.It Fl c , Fl -check

Check the script's syntax without executing it.

Exits with an error code if script is invalid.

.It Fl e , Fl -eval Ar string

Evaluate

.Ar string

as JavaScript.

.It Fl h , Fl -help

Print command-line options.

The output of this option is less detailed than this document.

.It Fl i , Fl -interactive

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

.It Fl p , Fl -print Ar string

Identical to

.Fl e ,

but prints the result.

.It Fl r , Fl -require Ar module

Preload the specified

.Ar module

at startup.

Follows `require()`'s module resolution rules.

.Ar module

may be either a path to a file, or a Node.js module name.

.It Fl v , Fl -version

Print node's version.

.El

.Bl -tag -width 6n

.It Ev FORCE_COLOR

Used to enable ANSI colorized output. The value may be one of:

.Ar 1

,

.Ar true

, or

.Ar an empty string

to

indicate 16-color support,

.Ar 2

to indicate 256-color support, or

.Ar 3

to indicate 16 million-color support. When 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.

.It Ev NO_COLOR

Alias for NODE_DISABLE_COLORS

.It Ev NODE_DEBUG Ar modules...

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

.It Ev NODE_DEBUG_NATIVE Ar modules...

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

.It Ev NODE_DISABLE_COLORS

When set to

.Ar 1 ,

colors will not be used in the REPL.

.It Ev NODE_EXTRA_CA_CERTS Ar file

When set, the well-known

.Dq root

CAs (like VeriSign) will be extended with the extra certificates in

.Ar file .

The file should consist of one or more trusted certificates in PEM format.

.Pp

If

.Ar file

is missing or misformatted, a message will be emitted once using

.Sy process.emitWarning() ,

but any errors are otherwise ignored.

.Pp

This environment variable is ignored when `node` runs as setuid root or

has Linux file capabilities set.

.Pp

The

.Ar NODE_EXTRA_CA_CERTS

environment variable is only read when the Node.js process is first launched.

Changing the value at runtime using

.Ar process.env.NODE_EXTRA_CA_CERTS

has no effect on the current process.

.It Ev NODE_ICU_DATA Ar file

Data path for ICU (Intl object) data.

Will extend linked-in data when compiled with small-icu support.

.It Ev NODE_NO_WARNINGS

When set to

.Ar 1 ,

process warnings are silenced.

.It Ev NODE_OPTIONS Ar options...

A space-separated list of command-line

.Ar 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

.Fl -print

or a script file.

.It Ev NODE_PATH Ar directories...

A colon-separated list of

.Ar directories

prefixed to the module search path.

.It Ev NODE_PENDING_DEPRECATION

When set to

.Ar 1 ,

emit pending deprecation warnings.

.It Ev NODE_PRESERVE_SYMLINKS

When set to

.Ar 1 ,

the module loader preserves symbolic links when resolving and caching modules.

.It Ev NODE_REDIRECT_WARNINGS Ar file

Write process warnings to the given

.Ar file

instead of printing to stderr.

Equivalent to passing

.Fl -redirect-warnings Ar file

on the command line.

.It Ev NODE_REPL_HISTORY Ar file

Path to the

.Ar file

used to store persistent REPL history.

The default path is

.Sy ~/.node_repl_history ,

which is overridden by this variable.

Setting the value to an empty string ("" or " ") will disable persistent REPL history.

.It Ev NODE_SKIP_PLATFORM_CHECK

When set to

.Ar 1 ,

the check for a supported platform is skipped during Node.js startup.

Node.js might not execute correctly.

Any issues encountered on unsupported platforms will not be fixed.

.It Ev NODE_TLS_REJECT_UNAUTHORIZED

When set to

.Ar 0 ,

TLS certificate validation is disabled.

.It Ev NODE_V8_COVERAGE Ar dir

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

.Ar dir .

.It Ev OPENSSL_CONF Ar 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

.Sy ./configure --openssl-fips .

.Pp

If the

.Fl -openssl-config

command-line option is used, this environment variable is ignored.

.It Ev SSL_CERT_DIR Ar dir

If

.Fl -use-openssl-ca

is enabled, this overrides and sets OpenSSL's directory containing trusted certificates.

.It Ev SSL_CERT_FILE Ar file

If

.Fl -use-openssl-ca

is enabled, this overrides and sets OpenSSL's file containing trusted certificates.

.It Ev UV_THREADPOOL_SIZE Ar size

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

.Ar size .

.El

Bugs are tracked in GitHub Issues:

.Sy https://github.com/nodejs/node/issues

Copyright Node.js contributors.

Node.js is available under the MIT license.

.Pp

Node.js also includes external libraries that are available under a variety of licenses.

See

.Sy https://github.com/nodejs/node/blob/HEAD/LICENSE

for the full license text.

Website:

.Sy https://nodejs.org/

.Pp

Documentation:

.Sy https://nodejs.org/api/

.Pp

GitHub repository and issue tracker:

.Sy https://github.com/nodejs/node

.Pp

IRC (general questions):

.Sy "libera.chat #node.js"

(unofficial)

Written and maintained by 1000+ contributors:

.Sy https://github.com/nodejs/node/blob/HEAD/AUTHORS