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Adds button for loading the previous video in a YT playlist
当前为
// ==UserScript==
// @name Play Youtube playlist in reverse order
// @namespace https://github.com/Dragosarus/
// @version 1.0
// @description Adds button for loading the previous video in a YT playlist
// @author Dragosarus
// @match www.youtube.com/watch?*list*
// @grant none
// @require http://code.jquery.com/jquery-latest.js
// ==/UserScript==
// Cookies (current session):
// pytplir_playPrevious - saves the button state between loads
(function() {
'use strict';
// Your code here...
$(document).ready(function() {
var activeColor = "rgb(64,166,255)";
var inactiveColor = "rgb(144,144,144)";
var player;
var arrow_up;
var arrow_down;
var playPrevious;
var btn_svg;
var redirectFlag = false;
// remove the need to refresh the page for the script to work properly
$("html")[0].addEventListener("yt-navigate-finish",init);
$("html")[0].addEventListener("yt-navigate-start",removeButton);
init();
function init() {
playPrevious = getCookie("pytplir_playPrevious");
if (playPrevious === "") { // cookie has not been set yet
playPrevious = false; // inital state
setCookie("pytplir_playPrevious",playPrevious);
}
// create button
arrow_up = document.createElementNS("http://www.w3.org/2000/svg","polygon");
arrow_down = document.createElementNS("http://www.w3.org/2000/svg","polygon");
btn_svg = document.createElementNS("http://www.w3.org/2000/svg","svg");
arrow_up.setAttribute("points","26,19 26,17 22,17 29,11 36,17 32,17 32,19");
arrow_up.addEventListener("click",onButtonClick);
arrow_down.setAttribute("points","26,20 26,22 22,22 29,28 36,22 32,22 32,20");
arrow_down.addEventListener("click",onButtonClick);
btn_svg.setAttribute("viewbox","0 0 40 40");
btn_svg.setAttribute("xmlns","http://www.w3.org/2000/svg");
btn_svg.setAttribute("width","50");
btn_svg.setAttribute("height","40");
btn_svg.setAttribute("id","plst-rev-btn");
btn_svg.appendChild(arrow_up);
btn_svg.appendChild(arrow_down);
setTimeout(addButton, 500);
setTimeout(start, 500);
}
function onButtonClick() { // toggle
playPrevious = !playPrevious;
setCookie("pytplir_playPrevious",playPrevious);
updateButtonState();
}
function addButton() {
withQuery(".ytd-playlist-panel-renderer > #top-level-buttons", function(res) {
if (!document.getElementById("plst-rev-btn")) {
res[0].appendChild(btn_svg);
updateButtonState();
}
});
}
function updateButtonState() {
if (playPrevious) { // play previous video
arrow_up.setAttribute("style","fill:"+activeColor);
arrow_down.setAttribute("style","fill:"+inactiveColor);
} else { // play next video
arrow_up.setAttribute("style","fill:"+inactiveColor);
arrow_down.setAttribute("style","fill:"+activeColor);
}
}
function removeButton() {
btn_svg.parentNode.removeChild(btn_svg);
}
function start() {
withQuery(".html5-main-video", function(res) {
player = res[0];
player.addEventListener("timeupdate",checkTime);
});
}
function withQuery(query, onSuccess) {
var res = $(query);
if (res) {
onSuccess(res);
return res;
} else { // not loaded yet => retry
setTimeout(function(){withQuery(query);}, 100);
}
}
function checkTime() {
var timeLeft = player.duration - player.currentTime;
if (playPrevious && timeLeft < 1.3 && !redirectFlag && !player.hasAttribute("loop")) {
redirectFlag = true;
redirect();
setTimeout(function() {redirectFlag = false;}, 1000);
}
}
function redirect() {
var previousURL = getPreviousURL();
if (previousURL) {
document.location.href = previousURL;
} else { // probably at start of playlist
player.pause(); // prevent next video from loading
}
}
function getPreviousURL(){
var query = document.querySelectorAll("#playlist-items");
var index;
var previousURL;
for (const a of Array.from(query).entries()) { // a = {index, element}
if (a[1].textContent.includes("▶")) { // Current video's position in playlist
index = a[0]; // index in query
if (index == 0) {break;} // start of list
previousURL = query[index-1].children[0].href;
return previousURL;
}
}
}
// adapted from https://www.w3schools.com/js/js_cookies.asp
function setCookie(cname, cvalue) {
document.cookie = cname + "=" + cvalue + ";sameSite=lax;path=www.youtube.com/watch";
}
function getCookie(cname) {
var name = cname + "=";
var decodedCookie = decodeURIComponent(document.cookie);
var ca = decodedCookie.split(';');
for(var i = 0; i <ca.length; i++) {
var c = ca[i];
while (c.charAt(0) == ' ') {
c = c.substring(1);
}
if (c.indexOf(name) == 0) {
var x = c.substring(name.length, c.length);
return ((x.toLowerCase() == "true") ? true : false);
}
}
return "";
}
});
})();