Write your first WebAssembly program
August 8, 2021 ≈ 45 seconds
Today, all the popular modern browsers provide WebAssembly support. But what you can do with it? — With WebAssembly you can run code written in multiple languages, like C, C++, and Rust at near-native speed in the browser!
It's easier to understand with code, so let's write our first WebAssembly program.
#include <emscripten.h>
int EMSCRIPTEN_KEEPALIVE multiply(int x, int y) {
return x * y;
}
That's just a function, written in C, which multiplies two numbers. With WebAssembly we can compile it into binary code (.wasm file) and use right from javascript! We would do it with Emscripten compiler.
On macOS, just run
brew install emscripten
Otherwise use this instructions
To compile our C function into .wasm file run
emcc -s hello.c -o hello.wasm --no-entry
Now we can include C function from .wasm file in javascript:
(async function(){
let { instance } = await WebAssembly.instantiateStreaming(fetch('hello.wasm'));
console.log(instance.exports.multiply(5, 8)); // 40
})();
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