microsoft/napajs

★ 9,184C++Audience · developerComplexity · 4/5LicenseSetup · moderate

Mindmap

mindmap
  root((napajs))
    What it does
      Multi-threaded JS
      Parallel computation
      Worker coordination
    Tech
      V8 engine
      Node.js package
      C++ core
    Use cases
      CPU-heavy tasks
      Backend services
      Parallel data work
    Audience
      Node.js devs
      Backend engineers

mindmap root((napajs)) What it does Multi-threaded JS Parallel computation Worker coordination Tech V8 engine Node.js package C++ core Use cases CPU-heavy tasks Backend services Parallel data work Audience Node.js devs Backend engineers

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Things people build with this

USE CASE 1

Run CPU-intensive JavaScript computations in parallel without blocking your main Node.js server thread.

USE CASE 2

Distribute recursive or math-heavy work across multiple threads to dramatically speed up processing time.

USE CASE 3

Build high-performance backend services in JavaScript that process data in parallel, similar to how Bing used it internally.

USE CASE 4

Embed a multi-threaded JavaScript runtime directly into a non-Node.js C++ application.

Tech stack

JavaScriptC++Node.jsV8

Getting it running

Difficulty · moderate Time to first run · 30min

Requires a C++ build toolchain and a compatible Node.js version, build status badges reference older CI services, so compatibility with current Node.js versions may need testing.

Use freely for any purpose including commercial, as long as you keep the copyright notice.

In plain English

Napa.js is a JavaScript runtime built by Microsoft that allows JavaScript code to run across multiple threads simultaneously. Standard JavaScript environments, including Node.js, run on a single thread, which means they can only do one thing at a time on the CPU. Napa.js was created to handle situations where that limitation causes performance problems, particularly for tasks that require heavy computation rather than waiting on network requests or file reads. The library was originally developed inside Bing to support high-performance backend services. It runs on the same underlying JavaScript engine that Chrome and Node.js use, called V8, but adds the ability to create multiple isolated JavaScript workers and coordinate work between them. Developers can broadcast code to all workers in a group, or send a specific task to any available worker and receive the result back asynchronously. Napa.js is distributed as a Node.js package, so developers install it the same way they install other Node.js libraries: with a single command. It also supports being embedded directly into other applications that do not use Node.js at all. The README includes short code examples and links to more complete tutorials covering use cases like parallel sorting, parallel estimation of mathematical values, and recursive calculations split across threads. The project is open source under the MIT license. Microsoft has not indicated active ongoing development in the README, and the build status badges reference older continuous integration services. Developers interested in running CPU-intensive JavaScript workloads in a multi-threaded way may find it useful as a reference or starting point.

Copy-paste prompts

Prompt 1

Using Napa.js, show me how to split a large array processing task across 4 worker threads and collect the combined results.

Prompt 2

I have a Node.js server that slows down during heavy math computations. Help me offload those computations to Napa.js worker threads.

Prompt 3

Write a Napa.js example that broadcasts a shared function to all workers and then runs parallel sorting on different chunks of an array.

Prompt 4

How do I install Napa.js in an existing Node.js project and run a first multi-threaded example that proves threads are working?

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