I don't know why

script.js

const L = 37, R = 39, U = 38, D = 40;
let a = [
    [L, U, R, D], [L, D, R, U],
    [R, U, L, D], [R, D, L, U],
    [U, L, D, R], [U, R, D, L],
    [D, L, U, R], [D, R, U, L]
];
let d = document;
let c = d.getElementsByTagName("canvas")[0];
let gdir = () => { return a[Math.floor(Math.random() * a.length)]; }
let sim = (co,t) => {
    let eA = d.createEvent("HTMLEvents");
    let eB = d.createEvent("HTMLEvents");
    eA.initEvent("keydown", true, true);
    eB.initEvent("keyup", true, true);
    eA.keyCode = co;
    eB.keyCode = co;
    c.dispatchEvent(eA);
    console.log(co, "down");
    setTimeout(() => { c.dispatchEvent(eB); console.log(co, "up") }, t);
};
let floop = () => {
    let dir = gdir();
    setTimeout(sim, 0, dir[0], 2000);
    setTimeout(sim, 2000, dir[1], 2000);
    setTimeout(sim, 4000, dir[2], 2000);
    setTimeout(sim, 6000, dir[3], 2000);
    setTimeout(floop, 8000);
};
floop();