Welcome to the official API reference documentation for Node.js!
Node.js is a JavaScript runtime built on the V8 JavaScript engine.
Report errors in this documentation in the issue tracker. See the contributing guide for directions on how to submit pull requests.
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.
Experimental features are subdivided into stages:
- 1.0 - Early development. Experimental features at this stage are unfinished and subject to substantial change.
- 1.1 - Active development. Experimental features at this stage are nearing minimum viability.
- 1.2 - Release candidate. Experimental features at this stage are hopefully ready to become stable. No further breaking changes are anticipated but may still occur in response to user feedback. We encourage user testing and feedback so that we can know that this feature is ready to be marked as stable.
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 Although this feature is unlikely to be removed and is still covered by semantic versioning guarantees, it is no longer actively maintained, and other alternatives are available.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 when authoring libraries. 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.
Every .html document has a corresponding .json document. This is for IDEs
and other utilities that consume the documentation.
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.