Node.js v13.0.0-nightly2019052912f5e0f8f8 Documentation

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.


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.

Use caution when making use of Experimental features, particularly within modules that are dependencies (or dependencies of dependencies) within a Node.js application. End users may not be aware that experimental features are being used, and may experience unexpected failures or behavior changes when API modifications occur. To help avoid such surprises, Experimental features may require a command-line flag to enable them, or may emit a process warning. By default, such warnings are printed to stderr and may be handled by attaching a listener to the 'warning' event.

JSON Output#

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

Syscalls and man pages#

System calls like open(2) and read(2) define the interface between user programs and the underlying operating system. Node.js functions which wrap a syscall, like, will document that. The docs link to the corresponding man pages (short for manual pages) which describe how the syscalls work.

Most Unix syscalls have Windows equivalents, but behavior may differ on Windows relative to Linux and macOS. For an example of the subtle ways in which it's sometimes impossible to replace Unix syscall semantics on Windows, see Node.js issue 4760.