Eww, a JS-only setTimeout polyfill??

setTimeoutGrossPolyfill.js

globalThis.setTimeout = (cb, num) => {
    const start = Date.now();

    function loop() {
        return new Promise((resolve) => {
            queueMicrotask(() => {
                const now = Date.now();
                const diff = now - start;
                if (diff < num) {
                    loop()
                        .then(() => resolve())
                    return;
                }
                resolve();
            })
        })
    }

    loop()
        .then(() => cb());
}

You could loop.then(resolve) instead of loop.then(() => resolve()). Also goes for loop.resolve(cb).