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Development Guide

QuickJS-ng is an open-source JavaScript engine that welcomes contributions from the community. This guide will help you get started with contributing to the project.

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Getting Started

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Prerequisites

  • Git
  • CMake 3.x or higher
  • A C compiler (GCC, Clang, MSVC, or TCC)
  • Make (on Unix-like systems)

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Cloning the Repository

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Building QuickJS-ng

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Quick Build

The simplest way to build QuickJS-ng is using the helper Makefile:
This will build the qjs and qjsc executables and other test tools.

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Debug Build

For development, you’ll want to create a debug build without optimizations:

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Manual CMake Build

If you prefer to use CMake directly (required on Windows):
For a debug build:

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Contribution Workflow

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Development Tools

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Code Generation

If you modify bytecode or built-in modules, regenerate the generated code:

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Syntax Checking

Verify that generated C code compiles correctly:

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C++ Compatibility

Test that the codebase compiles as C++:

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Statistics

View engine statistics and memory usage:

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Build Options

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Amalgamated Build

Create a single-file amalgamated build:
This generates quickjs-amalgam.zip containing a single quickjs-amalgam.c file.

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Shared Libraries

Build shared libraries instead of static:

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Examples

Build with examples enabled:

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Sanitizers

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Address Sanitizer (ASan) and Undefined Behavior Sanitizer (UBSan)

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Memory Sanitizer (MSan)

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CI/CD

QuickJS-ng uses GitHub Actions for continuous integration. The CI pipeline tests:
  • Multiple platforms: Linux, macOS, Windows, FreeBSD, OpenBSD
  • Multiple compilers: GCC, Clang, MSVC, TCC, MinGW
  • Multiple architectures: x86, x64, ARM64, RISC-V, s390x
  • Sanitizers: ASan, UBSan, MSan
  • Special builds: Emscripten, WASI, Android, iOS
  • Test262 compliance suite
All pull requests must pass CI checks before being merged.

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Coding Guidelines

  • Follow the existing code style and conventions
  • Write clear, self-documenting code with comments where necessary
  • Add tests for new features and bug fixes
  • Ensure all tests pass before submitting a pull request
  • Keep commits focused and atomic
  • Write descriptive commit messages

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Getting Help

If you need help or have questions:
  • Check the project documentation
  • Open an issue on GitHub for bugs or feature requests
  • Review existing issues and pull requests for similar topics

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Authors

QuickJS-ng is maintained by @bnoordhuis, @saghul, and many contributors. The original QuickJS engine was created by Fabrice Bellard and Charlie Gordon.