Clear YouTube playlist

clear_yt_playlist.js

// Go to https://www.youtube.com/playlist?list=WL

setInterval(function() {
    document.querySelector('#primary button[aria-label="Action menu"]').click();
    var things = document.evaluate('//span[contains(text(),"Watch later")]', document, null, XPathResult.ORDERED_NODE_SNAPSHOT_TYPE, null);
    for (var i = 0; i < things.snapshotLength; i++) {
        things.snapshotItem(i).click();
    }
}, 1000);