Random Hymn picker script for Tampermonkey or Greasemonkey browser extension. Works for Hymns and Children's Songbook.

randomHymn.js

// ==UserScript==
// @name         randomHymn.js
// @namespace    http://your.homepage/
// @version      0.1
// @description  enter something useful
// @author       You
// @match        https://www.lds.org/music/library/hymns*
// @match        https://www.lds.org/music/library/childrens-songbook*
// @grant        none
// ==/UserScript==

(function () {

    var randomInt = function (min, max) {
        return Math.round((max - min) * Math.random() + min);
    };

    var pickRandomHymn = function () {
        var hymns = document.querySelectorAll('#playlist tbody tr');
        var min = 1;
        var max = hymns.length - 1;
        var hymn = hymns[randomInt(min, max)];
        return hymn;
    };

    var scrollTo = function (element) {
        var rect = element.getBoundingClientRect()
        $('body').animate({
            scrollTop: rect.top + document.body.scrollTop - 40
        });
    };

    var highlight = function (element) {
        element.style.backgroundColor = 'yellow';
        setTimeout(function () {
            element.style.backgroundColor = null;
        }, 5000);
    };

    var styles = function (element, styles) {
        for (var prop in styles) {
            element.style[prop] = styles[prop];
        }
    };

    // create container
    var container = document.createElement('div');
    styles(container, {
        position: 'fixed',
        bottom: 0,
        left: 0
    });

    // create button
    var button = document.createElement('button');
    button.innerHTML = 'Random';
    button.onclick = function () {
        var hymn = pickRandomHymn();
        scrollTo(hymn);
        highlight(hymn);
    };

    // add to document
    container.appendChild(button);
    document.body.appendChild(container);
})();