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WebAssembly (WASM) for High Performance Apps · Lesson

WASM Memory Model & Management

Understand WebAssembly's linear memory model and how memory is allocated, accessed, and managed within WASM modules.

WASM Linear Memory: The Basics

WebAssembly uses a linear memory model. Think of it as a single, large, contiguous array of bytes, similar to how traditional programs manage memory.

  • This memory is separate from JavaScript's memory.
  • It's accessed by WASM modules as a flat address space, starting from address 0.
  • All data (integers, floats, strings, arrays) lives within this single memory block.

The `WebAssembly.Memory` Object

In JavaScript, WASM memory is represented by the WebAssembly.Memory object. This object holds the actual memory buffer.

You can create it:

  • When instantiating a WASM module, it can declare and create its own memory.
  • You can also pass an existing WebAssembly.Memory instance from JavaScript to the module.
const memory = new WebAssembly.Memory({
  initial: 1, // Start with 1 page (64KB)
  maximum: 10 // Max allowed 10 pages
});

// This 'memory' object is then passed to the
// WASM module during instantiation.

All lessons in this course

  1. Passing Complex Data Structures
  2. WASM Memory Model & Management
  3. Shared Memory & Atomics
  4. Growing & Managing Linear Memory
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