Missing Standard Library For Multithreading In Javascript 2025

The missing standard library for multithreading in JavaScript (Works in Node.js, Deno, Bun, Web browser)

Multithreading is a TypeScript library that brings robust, Rust-inspired concurrency primitives to the JavaScript ecosystem. It provides a thread-pool architecture, strict memory safety semantics, and synchronization primitives like Mutexes, Read-Write Locks, and Condition Variables.

This library is designed to abstract away the complexity of managing WebWorkers, serialization, and SharedArrayBuffer complexities, allowing developers to write multi-threaded code that looks and feels like standard asynchronous JavaScript.

JavaScript is traditionally single-threaded. To achieve true parallelism, this library uses Web Workers. However, unlike standard Workers, this library offers:

The entry point for most operations is the spawn function. This submits a task to the thread pool and returns a handle to await the result.

Because Web Workers run in a completely isolated context, functions passed to spawn cannot capture variables from their outer scope. If you attempt to use a variable inside the worker that was defined outside of it, the code will fail.

To get data from your main thread into the worker, you have to use the move() function.

The move function accepts variadic arguments. These arguments are passed to the worker function in the order they were provided. Despite the name, move handles data in two ways:

SharedJsonBuffer enables Mutex-protected shared memory for JSON objects, eliminating the overhead of postMessage data copying. Unlike standard buffers, it handles serialization automatically. It supports partial updates, re-serializing only changed bytes rather than the entire object tree for high-performance state synchronization.

When multiple threads access shared memory (via SharedArrayBuffer), race conditions occur. This library provides primitives to synchronize access safely.

Source: HackerNews