Skip Google Music

index.js

// This script will monitor the Google Music page and skip songs you've already downvoted.
// Google doesn't do this automatically for some weird reason, so this hacks around that.
// Note that you're limited to somewhere around five skips per hour per station, so you
// can pretty quickly run into a scenario where this won't work. In the case that you want
// to stop the script, just run clearInterval(skipper) after this script.

var skipper = setInterval(function() {
    // Grab the rating container (first of two with the same class)
    var ratingContainer = document.getElementsByClassName('rating-container')[0];
    
    // The down thumb is the middle element
    var downThumbButton = ratingContainer.children[1];
    
    // Get the "title" attribute from the button
    var titleAttr = downThumbButton.attributes.title.textContent;

    // Check if the title is prefixed with "Undo" in the case that you've already thumbed
    var isDownThumbed = titleAttr.startsWith('Undo');

    // If it is thumbed down, "click" the next / skip button
    if (isDownThumbed) {
        document.getElementById('player-bar-forward').click();
    }
}, 5000);

@glichtenstein
Use greasemonkey for firefox https://addons.mozilla.org/en-US/firefox/addon/greasemonkey/
or tampermonkey for chrome.