What is WebAssembly?

WebAssembly (WASM) is a compact binary instruction format designed as a portable compilation target for programming languages. It enables high-performance applications to run on the web.

Core Features

Feature	Description
Binary format	Efficient binary-encoded code
Stack machine	Push/pop based architecture
Type safety	Strong type system, only four value types
Memory model	Dynamically growable linear memory
Sandboxed	Isolated execution environment

How It Works

WASM's simple example:

;; WAT (WebAssembly Text Format) — human-readable representation
(module
  (func $add (param i32 i32) (result i32)
    local.get 0
    local.get 1
    i32.add)
  (export "add" (func $add)))

From JavaScript:

// Exported functions can be called directly
const result = instance.exports.add(40, 2);
console.log(result); // 42

WebAssembly vs JavaScript

Aspect	JavaScript	WebAssembly
Format	Text	Binary
Parse speed	Slower	Faster
Execution	JIT compiled	Direct execution
Type system	Dynamic	Static
GC support	Built-in	Limited
DOM access	Direct	Via JS interop

When to Use WASM

Use WebAssembly in these scenarios:

• Performance-critical code — Image/video processing, game engines, codecs
• Port existing codebases — Reuse C/C++/Rust libraries in Web
• Compute-intensive tasks — Scientific computing, encryption, compression
• Near-native performance — Signal processing, physics simulation

TIP

WebAssembly doesn't replace JavaScript — it's a complement to JavaScript. Use WASM for compute-intensive tasks while keeping JavaScript for DOM manipulation and business logic.

Browser Support

All modern browsers support WebAssembly:

Browser	Supported From
Chrome	57+
Firefox	52+
Safari	11+
Edge	16+

What's Next

Now that you know what WebAssembly is, let's set up the development environment.