Skip to content
A TypeScript to WebAssembly compiler πŸš€
Branch: master
Clone or download
Type Name Latest commit message Commit time
Failed to load latest commit information.
bin Enable source maps out of the box (#519) Feb 28, 2019
cli Correct asc output stream typings, fixes #485 Feb 21, 2019
examples General cleanup (#525) Mar 8, 2019
lib Rebuild examples Feb 28, 2019
media Add architecture diagram to media Mar 18, 2018
src Use lazy initializations for decorators and type parameters in parser (… Mar 22, 2019
std Implement TypedArray#reverse (#532) Mar 8, 2019
tests Fix enum initialization (#545) Mar 18, 2019
.gitattributes Update Binaryen to latest; Various fixes Oct 11, 2018
.travis.yml General cleanup (#525) Mar 8, 2019 Add contributing guidelines Mar 16, 2018 Update Jan 30, 2019
NOTICE General cleanup (#525) Mar 8, 2019
package-lock.json Update Binaryen to latest nightly Mar 8, 2019
package.json Fix postinstall script (#538) Mar 11, 2019
tsconfig-base.json CString/CArray was an illusion; Update and test tsconfig files Dec 11, 2017
tsconfig-docs.json Set up documentation generation Mar 19, 2018
tslint.json Implement Array.isArray and Array#copyWithin (#331) Nov 12, 2018


Build Status

AssemblyScript compiles strictly typed TypeScript (basically JavaScript with types) to WebAssembly using Binaryen. It generates lean and mean WebAssembly modules while being just an npm install away.

Try it out in WebAssembly Studio!

Our Sponsors

Our Backers

The core team members and most contributors do this open source work in their free time. If you use AssemblyScript for a serious task or plan to do so, and you'd like us to invest more time on it, please donate to our OpenCollective. By sponsoring this project, your logo will show up above. Thank you so much for your support!


AssemblyScript was frictionless. Not only does it allow you to use TypeScript to write WebAssembly, [...] it also produces glue-free WebAssembly modules that are very small with decent performance. – Surma, Replacing a hot path in your app's JavaScript with WebAssembly (Feb 16, 2019)

Perhaps the fundamental issue [to get a small .wasm file] is that JavaScript is the only language for which the Web runtime is a perfect fit. Close relatives that were designed to compile to it, like TypeScript, can be very efficient as well. But languages like C, C++, Rust, and so forth were not originally designed for that purpose. – Alon Zakai, Small WebAssembly Binaries with Rust + Emscripten (Apr 18, 2018)

JavaScript's heyday as the only browser language is over, but most web developers are used to writing JavaScript, and learning a new syntax just to get access to WebAssembly is not (always) ideal. If only there was something in to bridge the gap… – Jani Tarvainen, TypeScript is the bridge between JavaScript and WebAssembly (Feb 20, 2018)

I do think [compiling TypeScript into WASM] is tremendously useful. It allows JavaScript developers to create WASM modules without having to learn C. – Colin Eberhardt, Exploring different approaches to building WebAssembly modules (Oct 17, 2017)

Getting started

All the details are provided in the AssemblyScript wiki - make sure to pay it a visit. With that being said, the easiest way to get started with AssemblyScript is to point npm at the GitHub repository (for now)

$> npm install --save-dev AssemblyScript/assemblyscript

followed by scaffolding a new project including the necessary configuration files, for example in the current directory:

$> npx asinit .

Once the project is set up, it's just a matter of using your existing TypeScript tooling while coding, and using the CLI to build to WebAssembly, either manually, or using (and maybe modifying) the generated build task in the generated package.json:

$> npm run asbuild

The CLI API can also be used programmatically.

If you rather prefer an installation suitable for development, pretty much the same can be achieved by cloning the GitHub repository instead:

$> git clone
$> cd assemblyscript
$> npm install
$> npm link

Note that a fresh clone of the compiler will use the distribution files in dist/, but it can also run the sources directly through ts-node after an npm run clean, which is useful in development. This condition can also be checked by running asc -v (it is running the sources if it states -dev).



To build an UMD bundle to dist/assemblyscript.js (depends on binaryen.js), including a browser version of asc to dist/asc.js (depends on assemblyscript.js):

$> npm run build

Cleaning the distribution files (again):

$> npm run clean

Linting potential changes:

$> npm run check

Running the tests:

$> npm test

Running everything in order (lint, clean, test, build, test):

$> npm run all
You can’t perform that action at this time.