What is WebAssembly?
For a little over two decades now, we’ve had only one programming language available to use natively in a web browser: the famous and infamous JavaScript. The slow death of third-party binary plug-ins has ruled out other languages, such as Java and Flash’s ActionScript, as the old first-class citizens for web development. Other web languages, like CoffeeScript, are just compiled to JavaScript at the end of the day.
But now we have a new possibility: WebAssembly, or Wasm for short.
WebAssembly is a small, fast binary format that promises near-native performance for web applications. Plus, WebAssembly is designed to be a compilation target for any language, JavaScript just being just one of them.
With every major browser now supporting WebAssembly, it’s time to start thinking seriously about writing client-side apps for the web that can be compiled as WebAssembly.
It is worth noting that WebAssembly apps aren’t meant to replace JavaScript apps — at least, not yet. Instead, think of WebAssembly as a companion to JavaScript. Where JavaScript is flexible, dynamically typed, and delivered through human-readable source code, WebAssembly is high-speed, strongly typed, and delivered via a compact binary format.
Developers should consider WebAssembly for performance-intensive use cases such as games, music streaming, video editing, and CAD applications. Many web services have already made the move, such as Google Earth. Figma, a collaborative drawing and diagramming app, turned to WebAssembly to cut load times and execution speed even when WebAssembly was relatively new.
Traven West
How WebAssembly works
WebAssembly, developed by the W3C, is in the words of its creators a “compilation target.” Developers don’t write WebAssembly directly; they write in the language of their choice, which is then compiled into WebAssembly bytecode. The bytecode is then run on the client—typically in a web browser—where it’s translated into native machine code and executed at high speed.