- Assertion Testing
- Async Hooks
- C++ Addons
- C/C++ Addons - N-API
- Child Processes
- Command Line Options
- Deprecated APIs
- ECMAScript Modules
- File System
- Performance Hooks
- Query Strings
- String Decoder
Table of Contents
About this Documentation#
The goal of this documentation is to comprehensively explain the Node.js API, both from a reference as well as a conceptual point of view. Each section describes a built-in module or high-level concept.
Where appropriate, property types, method arguments, and the arguments provided to event handlers are detailed in a list underneath the topic heading.
Every file is generated based on the corresponding
.md file in the
doc/api/ folder in Node.js's source tree. The documentation is generated
tools/doc/generate.js program. An HTML template is located at
Throughout the documentation are indications of a section's stability. The Node.js API is still somewhat changing, and as it matures, certain parts are more reliable than others. Some 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 and in the process of being redesigned.
The stability indices are as follows:
Note: Caution must be used when making use of
particularly within modules that may be used as dependencies (or dependencies
of dependencies) within a Node.js application. End users may not be aware that
experimental features are being used, and therefore may experience unexpected
failures or behavior changes when API modifications occur. To help avoid such
Experimental features may require a command-line flag to
explicitly enable them, or may cause a process warning to be emitted.
By default, such warnings are printed to
stderr and may be handled by
attaching a listener to the
.html document has a corresponding
.json document presenting
the same information in a structured manner. This feature is
experimental, and added for the benefit of IDEs and other utilities that
wish to do programmatic things with 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 functions which simply wrap a syscall,
fs.open(), 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 issue 4760.