Video playback rate hotkeys for Coursera, through Tampermonkey

coursera-playback-rate-hotkeys-tampermonkey.js

// ==UserScript==
// @name         Coursera playback rate hotkeys
// @namespace    http://tampermonkey.net/
// @version      1.0
// @description  Add button listeners to + and - keys for changing the video playback rate on Coursera
// @author       You
// @match        https://www.coursera.org/learn/*
// @grant        none
// ==/UserScript==

(function() {
    'use strict';

    // Attach event listeners
    document.body.addEventListener("keypress", ({key}) => {
      switch (key) {
          case "-": return document.querySelector("button[aria-label='decrease playback rate']").click();
          case "+": return document.querySelector("button[aria-label='increase playback rate']").click();
      }
    });

    // Add text informing about playback rate controls
    document.querySelector("style").sheet.insertRule(`.rc-PlayButton:before {
        content: "+ and - controls playback rate with TamperMonkey";
        font-size: 16pt;
        background-color: white;
        padding: 5pt;
        opacity: 0.8;
        border-radius: 5pt;
    }`);
})();