Keep solo element on page

clean.js

const onPageReady = (fn) => {
    if (document.readyState !== 'loading') {
        fn();
    } else {
        document.addEventListener('DOMContentLoaded', fn);
    }
};

onPageReady(() => {
    const doClean = (el) => {
        const parent = el.parentElement;
        for (const child of Array.from(parent.childNodes)) {
            if (child !== el) {
                child.remove();
            }
        }

        el.style.padding = 0;
        el.style.margin = 0;

        if (parent !== document.body) {
            doClean(parent);
        }
    };

    const playerEl = document.querySelector('#cdnplayer'); // <<<<<<<<<<<
    doClean(playerEl);
    playerEl.style.width = '100vw';
    playerEl.style.height = '100vh';
});