install Emscripten

Example C/C++ Runtime Code

create file hello_world.c

#include <stdio.h>
 
int main() {
  printf("hello, world!\n");
  return 0;
}

Compiling to JavaScript

emcc hello_world.c

this should generate 2 files:

• a.out.js - JavaScript file
• a.out.wasm - WebAssembly file

you can run them using Node.js

node a.out.js

this prints “hello, world!” to console

Generating HTML

emcc hello_world.c -o hello.html

you can open hello.html in a web browser

Optimizing Code

-01 minor optimization

emcc -01 hello_world.c

-02 aggressive optimization

emcc -02 hello_world.c