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);

Works well. I added a check for title because it would log errors to the console when no song is currently playing and I reduced the interval to 500 ms to make sure it skips as soon as possible.

I've also added another timer which hides the songs from the queue. It's purely cosmetic. It will still show blank entries in the list because changing display to none instead seems to break everything.

let gmusicSkipper = setInterval(function()
{
    let container = document.getElementsByClassName('rating-container')[0];
    let button = container.children[1];

    if (button)
    {
        let title = button.attributes.title;

        if (title && title.textContent.startsWith('Undo'))
            document.getElementById('player-bar-forward').click();
    }
}, 500);


let gmusicHider = setInterval(function()
{
    let table = document.getElementsByClassName("song-table mini")[0];
    if (!table || !table.rows)
        return;

    for (let r of table.rows)
    {
        if (!r)
            continue;

        for (let c of r.cells)
        {
            if (c.dataset.col == "rating")
            {
                if (c.dataset.rating == "1")
                {
                    r.style.setProperty("visibility", "hidden");
                    break;
                }
            }
        }
    }
}, 1000);

Amusingly, data-rating is 5 for thumb-up and 1 for thumb-down, showing that it's really a simplified UI for a 5-star rating instead of a "don't play that song".

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