Learn EMSCRIPTEN with Real Code Examples

Updated Nov 25, 2025

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Installation Setup

Install Emscripten SDK (`emsdk`) from official repository

Activate and set up environment using `emsdk install` and `emsdk activate`

Add Emscripten tools to PATH

Verify installation using `emcc --version`

Compile a simple C/C++ program to WebAssembly using `emcc`

Environment Setup

Install Emscripten SDK (`emsdk`) and activate it

Add tools to system PATH

Install required C/C++ compiler toolchains

Set environment variables for compilation

Test by compiling and running a sample project

Config Files

CMakeLists.txt - optional build system

Makefile - optional build automation

emsdk/ - Emscripten SDK installation

source files (.c/.cpp)

Output files (.wasm, .js, .html)

Cli Commands

emcc source.c -o output.html -> compile to Wasm + HTML

emcc -O3 source.c -o output.js -> optimized Wasm + JS

emrun output.html -> run locally in browser

emcc --bind source.cpp -o output.js -> embind for JS integration

emcc -s WASM=1 source.c -o output.wasm -> generate Wasm binary

Internationalization

UTF-8 supported by default

Localization handled via application logic in JS/C++

Browser locale APIs can be used

Text rendering via WebGL/Canvas supports multiple languages

Developers handle translation and input encoding

Accessibility

Runs in standard browsers supporting WebAssembly

Cross-platform (Windows, macOS, Linux -> web)

Works on mobile browsers with WebAssembly support

Integrates with JavaScript accessibility features

No native OS-level accessibility APIs

Ui Styling

Emscripten does not provide UI by itself

Integrates with HTML/CSS and JS for rendering

Canvas, WebGL, and WebAudio used for multimedia apps

Frontend frameworks can be combined

UI updates occur via JS glue code interacting with browser DOM

State Management

In-browser state is temporary unless stored in MEMFS or IndexedDB

No persistent OS-level storage

Environment variables simulated via JavaScript

Multithreaded state can use SharedArrayBuffer

External APIs/databases required for permanent storage

Data Management

Input via HTML forms, network requests, or files

Output via DOM updates, canvas, audio, or network

Virtual file system emulates file operations

Persistent storage via IndexedDB

Memory limits imposed by browser environment