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Video Speed Control with Keyboard

Control any HTML5 video playback speed by pressing shortcut keys. See source code comment for the shortcut keymap.

Verze ze dne 02. 04. 2020. Zobrazit nejnovější verzi.

// ==UserScript==

// @name                Video Speed Control with Keyboard
// @description         Control any HTML5 video playback speed by pressing shortcut keys. See source code comment for the shortcut keymap.
// @version             3.1

// @namespace           io.github.ni554n
// @include             *

// @supportURL          https://github.com/ni554n/userscripts/issues
// @license             MIT

// @author              Nissan Ahmed
// @homepageURL         https://ni554n.github.io/
// @contributionURL     https://paypal.me/ni554n

// ==/UserScript==

/* Keymap:
 * ┌─────┬───────┐
 * │ Key │ Speed │
 * ├─────┼───────┤
 * │  ,  │ -0.5x │
 * ├─────┼───────┤
 * │  .  │ +0.5x │
 * ├─────┼───────┤
 * │  ;  │   1x  │
 * ├─────┼───────┤
 * │  '  │  2.5x │
 * ├─────┼───────┤
 * │  [  │   2x  │
 * ├─────┼───────┤
 * │  ]  │ 1.75x │
 * └─────┴───────┘
 */

// Stores currently playing video element reference for changing the speed later.
let video;

// Stores currently selected speed. Also acts as default / initial playback speed for all video.
let speed = 1;

/* The "playing" event always fires automatically at the start of a video but "play" event is not.
 * After using the event for the initial key registration, "play" event is used for capturing the active video reference.
 */
document.addEventListener("playing", registerShortcutKeys, { capture: true, once: true });
document.addEventListener("playing", restoreSpeed, { capture: true });
document.addEventListener("play", captureActiveVideoElement, true);

function registerShortcutKeys(event) {
  captureActiveVideoElement(event);

  document.addEventListener("keydown", handlePressedKey);
}

function restoreSpeed(event) {
  if (event.target.playbackRate !== speed) event.target.playbackRate = speed;
}

function captureActiveVideoElement(event) {
  video = event.target;
  speed = video.playbackRate;
}

function handlePressedKey(event) {
  // If the pressed key is coming from any input field, do nothing.
  const target = event.target;
  if (target.localName === "input" || target.localName === "textarea" || target.isContentEditable) return;

  // Mapping keys with actions.
  const key = event.key;
  if (key === ",") video.playbackRate -= 0.5;
  else if (key === ".") video.playbackRate += 0.5;
  else if (key === ";") video.playbackRate = 1;
  else if (key === "\'") video.playbackRate = 2.5;
  else if (key === "[") video.playbackRate = 2;
  else if (key === "]") video.playbackRate = 1.75;

  // Saving the speed for next resume or video playback.
  speed = video.playbackRate;
}