 AssemblyScript
=================
[](https://www.npmjs.com/package/assemblyscript)
[](https://travis-ci.org/AssemblyScript/assemblyscript)
[](https://build.snapcraft.io/user/AssemblyScript/assemblyscript)
**AssemblyScript** compiles strictly typed [TypeScript](http://www.typescriptlang.org) (basically JavaScript with types) to [WebAssembly](http://webassembly.org) using [Binaryen](https://github.com/WebAssembly/binaryen). It generates lean and mean WebAssembly modules while being just an `npm install` away.
Try it out in [WebAssembly Studio](https://webassembly.studio)!
Motivation
----------
> Being able to write C-performance code in TypeScript feels so good – Ari on [Slack](https://assemblyscript.slack.com) (Apr 19, 2018)
> 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](https://kripken.github.io/blog/binaryen/2018/04/18/rust-emscripten.html) (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](https://malloc.fi/typescript-bridge-javascript-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](http://blog.scottlogic.com/2017/10/17/wasm-mandelbrot.html) (Oct 17, 2017)
Getting started
---------------
All the details are provided in the [AssemblyScript wiki](https://github.com/AssemblyScript/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](https://github.com/AssemblyScript/assemblyscript/wiki/Using-the-CLI#scaffolding-with-asinit) 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](https://code.visualstudio.com) while coding, and [using the CLI](https://github.com/AssemblyScript/assemblyscript/wiki/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](./cli).
If you rather prefer an installation suitable for development, pretty much the same can be achieved by cloning the GitHub repository instead:
```
$> git clone https://github.com/AssemblyScript/assemblyscript.git
$> 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](./src) 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`).
Examples
--------
* **[Conway's Game of Life](./examples/game-of-life)** [ [demo](https://rawgit.com/AssemblyScript/assemblyscript/master/examples/game-of-life/index.html) | [fiddle](https://webassembly.studio/?f=gvuw4enb3qk) ]
Continuously updates the cellular automaton and visualizes its state on a canvas.
* **[Mandelbrot Set](./examples/mandelbrot)** [ [demo](https://rawgit.com/AssemblyScript/assemblyscript/master/examples/mandelbrot/index.html) | [fiddle](https://webassembly.studio/?f=pne1undq5g) ]
Renders the Mandelbrot set to a canvas.
* **[i64 polyfill](./examples/i64-polyfill)**
Exposes WebAssembly's i64 operations to JavaScript using 32-bit integers (low and high bits).
* **[PSON decoder](./examples/pson)**
A simple decoder for the PSON binary format.
* **[WASM parser](./lib/parse)**
A WebAssembly binary parser in WebAssembly.
Building
--------
To build an UMD bundle to `dist/assemblyscript.js` (depends on [binaryen.js](https://github.com/AssemblyScript/binaryen.js)), including a browser version of asc to `dist/asc.js` (depends on assemblyscript.js):
```
$> npm run build
```
Cleaning the distributions files (again):
```
$> npm run clean
```
Linting potential changes:
```
$> npm run lint
```
Running the [tests](./tests):
```
$> npm test
```
Running everything in order (lint, clean, test, build, test):
```
$> npm run all
```