About this documentation | Node.js v18.11.0 Documentation

Node.js

- About this documentation
- Usage and example

- Assertion testing
- Asynchronous context tracking
- Async hooks
- Buffer
- C++ addons
- C/C++ addons with Node-API
- C++ embedder API
- Child processes
- Cluster
- Command-line options
- Console
- Corepack
- Crypto
- Debugger
- Deprecated APIs
- Diagnostics Channel
- DNS
- Domain
- Errors
- Events
- File system
- Globals
- HTTP
- HTTP/2
- HTTPS
- Inspector
- Internationalization
- Modules: CommonJS modules
- Modules: ECMAScript modules
- Modules: `node:module` API
- Modules: Packages
- Net
- OS
- Path
- Performance hooks
- Permissions
- Process
- Punycode
- Query strings
- Readline
- REPL
- Report
- Stream
- String decoder
- Test runner
- Timers
- TLS/SSL
- Trace events
- TTY
- UDP/datagram
- URL
- Utilities
- V8
- VM
- WASI
- Web Crypto API
- Web Streams API
- Worker threads
- Zlib

- Code repository and issue tracker

Table of contents

- About this documentation
  - Contributing
  - Stability index
  - Stability overview
  - JSON output
  - System calls and man pages

## About this documentation#

Welcome to the official API reference documentation for Node.js!

Node.js is a JavaScript runtime built on the V8 JavaScript engine.

### Contributing#

Report errors in this documentation in the issue tracker. See the contributing guide for directions on how to submit pull requests.

### Stability index#

Throughout the documentation are indications of a section's stability. Some APIs are so proven and so relied upon that they are unlikely to ever change at all. Others are brand new and experimental, or known to be hazardous.

The stability indices are as follows:

Stability: 0 - Deprecated. The feature may emit warnings. Backward compatibility is not guaranteed.

Stability: 1 - Experimental. The feature is not subject to semantic versioning rules. Non-backward compatible changes or removal may occur in any future release. Use of the feature is not recommended in production environments.

Stability: 2 - Stable. Compatibility with the npm ecosystem is a high priority.

Stability: 3 - Legacy. Although this feature is unlikely to be removed and is still covered by semantic versioning guarantees, it is no longer actively maintained, and other alternatives are available.

Features are marked as legacy rather than being deprecated if their use does no harm, and they are widely relied upon within the npm ecosystem. Bugs found in legacy features are unlikely to be fixed.

Use caution when making use of Experimental features, particularly within modules. Users may not be aware that experimental features are being used. Bugs or behavior changes may surprise users when Experimental API modifications occur. To avoid surprises, use of an Experimental feature may need a command-line flag. Experimental features may also emit a warning.

### Stability overview#

API | Stability
--- | ---
assert | (2) Stable
async_hooks | (1) Experimental
asynchronous_context_tracking | (2) Stable
buffer | (2) Stable
child_process | (2) Stable
cluster | (2) Stable
console | (2) Stable
crypto | (2) Stable
dgram | (2) Stable
diagnostics_channel | (1) Experimental
dns | (2) Stable
domain | (0) Deprecated
fs | (2) Stable
http | (2) Stable
http/2 | (2) Stable
https | (2) Stable
inspector | (2) Stable
module | (2) Stable
os | (2) Stable
path | (2) Stable
performance_measurement_apis | (2) Stable
punycode | (0) Deprecated
querystring | (2) Stable
readline | (2) Stable
repl | (2) Stable
stream | (2) Stable
string_decoder | (2) Stable
test_runner | (1) Experimental
timers | (2) Stable
tls_(ssl) | (2) Stable
trace_events | (1) Experimental
tty | (2) Stable
url | (2) Stable
util | (2) Stable
vm | (2) Stable
web_crypto_api | (1) Experimental
web_streams_api | (1) Experimental.
webassembly_system_interface_(wasi) | (1) Experimental
worker_threads | (2) Stable
zlib | (2) Stable

### JSON output#

Added in: v0.6.12

Every `.html` document has a corresponding `.json` document. This is for IDEs and other utilities that consume the documentation.

### System calls and man pages#

Node.js functions which wrap a system call will document that. The docs link to the corresponding man pages which describe how the system call works.

Most Unix system calls have Windows analogues. Still, behavior differences may be unavoidable.