February 4, 2019

308 words 2 mins read



Napa.js: a multi-threaded JavaScript runtime

repo name microsoft/napajs
repo link https://github.com/microsoft/napajs
language C++
size (curr.) 13058 kB
stars (curr.) 8810
created 2017-07-18
license Other

Build Status for Linux/MacOS Build Status for Windows npm version Downloads


Napa.js is a multi-threaded JavaScript runtime built on V8, which was originally designed to develop highly iterative services with non-compromised performance in Bing. As it evolves, we find it useful to complement Node.js in CPU-bound tasks, with the capability of executing JavaScript in multiple V8 isolates and communicating between them. Napa.js is exposed as a Node.js module, while it can also be embedded in a host process without Node.js dependency.


Install the latest stable version:

npm install napajs

Other options can be found in Build Napa.js.

Quick Start

const napa = require('napajs');
const zone1 = napa.zone.create('zone1', { workers: 4 });

// Broadcast code to all 4 workers in 'zone1'.
zone1.broadcast('console.log("hello world");');

// Execute an anonymous function in any worker thread in 'zone1'.
    (text) => text, 
    ['hello napa'])
    .then((result) => {

More examples:


  • Multi-threaded JavaScript runtime.
  • Node.js compatible module architecture with NPM support.
  • API for object transportation, object sharing and synchronization across JavaScript threads.
  • API for pluggable logging, metric and memory allocator.
  • Distributed as a Node.js module, as well as supporting embed scenarios.



You can contribute to Napa.js in following ways:

  • Report issues and help us verify fixes as they are checked in.
  • Review the source code changes.
  • Contribute to core module compatibility with Node.
  • Contribute bug fixes.

This project has adopted the Microsoft Open Source Code of Conduct. For more information see the Code of Conduct FAQ or contact opencode@microsoft.com with any additional questions or comments.


Copyright (c) Microsoft Corporation. All rights reserved.

Licensed under the MIT License.

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