Turn Youtube player to theater mode automatically.
// ==UserScript==
// @name Youtube Automatic Theater
// @namespace http://tampermonkey.net/
// @version 2024-03-02
// @description Turn Youtube player to theater mode automatically.
// @author Santeri Hetekivi
// @match *://*.youtube.com/*
// @icon https://www.google.com/s2/favicons?sz=64&domain=youtube.com
// @grant none
// @license Apache-2.0
// ==/UserScript==
(function () {
'use strict';
/**
* Get element with selector and call callback with it.
* @param {string} selector Selector for the element.
* @param {function} callback Callback function to call with the element.
*/
function forElement(selector, callback) {
// Init forElement.timeoutCount.
if (forElement.timeoutCount === undefined) {
forElement.timeoutCount = {}
}
// Init forElement.timeoutCount[selector].
if (forElement.timeoutCount[selector] === undefined) {
forElement.timeoutCount[selector] = 0
}
// Get element.
const element = document.querySelector(selector)
// If element not found.
if (element === null) {
// try again after timeout.
setTimeout(
function () {
forElement(selector, callback)
},
(
// Base timeout.
100
*
// Increase timeout after each try.
(forElement.timeoutCount[selector]++)
)
)
}
// If element found
else {
// reset timeout count
forElement.timeoutCount[selector] = 0
// and call callback with element.
callback(element)
}
}
// Init previous video id.
let videoIdPrevious = null;
/**
* Run on url change.
*/
function onUrlChange() {
// Get video id from url.
const videoId = (new URLSearchParams(window.location.search)).get("v");
// If
if (
// did not get video id
videoId === null
||
// or video id did not change
videoId === videoIdPrevious
) {
// just return.
return
}
// Update previous video id.
videoIdPrevious = videoId;
// Run for
forElement(
// Youtube page manager that has video id
".ytd-page-manager[video-id]",
function (manager) {
// If theater mode is on
if (manager.theater) {
// just return.
return
}
// Run for
forElement(
// Youtube size button
".ytp-size-button",
function (button) {
/**
* Turn Youtube player to theater mode.
*/
function toTheaterMode() {
// If manager is already in theater mode
if (manager.theater) {
// just return.
return
}
// Click the size button.
button.click()
// Init timeout count.
if (toTheaterMode.timeoutCount === undefined)
toTheaterMode.timeoutCount = 0
// Try again after timeout.
setTimeout(
function () {
toTheaterMode()
},
(
// Base timeout.
100
*
// Increase timeout after each try.
(toTheaterMode.timeoutCount++)
)
)
}
// Call turning to theater mode.
toTheaterMode()
}
)
}
)
}
// Add event listener for
window.addEventListener(
// Youtube page data updated event.
'yt-page-data-updated',
function () {
onUrlChange();
}
);
// Run on url change once on first load.
onUrlChange();
})();