mylib.c compiled to screepsbot.wasm

typedef struct {
    int x;
    int y;
} mystruct;

int foo(mystruct v) {
    return v.x + v.y;
}

screeps.main.js

const bytecode = require('screepsbot');

const wasmModule = new WebAssembly.Module(bytecode);

const imports = {
    env: {
        memoryBase: 0,
        tableBase: 0,
        memory: new WebAssembly.Memory({ initial: 256 }),
        table: new WebAssembly.Table({ initial: 16, element: 'anyfunc' }),
        abort: (...args) => console.warn(...args),
    }
};

const wasmInstance = new WebAssembly.Instance(wasmModule, imports);
console.log(wasmInstance.exports._foo({x: 1, y: 2})); // prints 0