Play Youtube playlist in reverse order

Adds button for loading the previous video in a YT playlist

目前為 2020-07-27 提交的版本,檢視 最新版本

您需要先安裝使用者腳本管理器擴展,如 TampermonkeyGreasemonkeyViolentmonkey 之後才能安裝該腳本。

You will need to install an extension such as Tampermonkey to install this script.

您需要先安裝使用者腳本管理器擴充功能,如 TampermonkeyViolentmonkey 後才能安裝該腳本。

您需要先安裝使用者腳本管理器擴充功能,如 TampermonkeyUserscripts 後才能安裝該腳本。

你需要先安裝一款使用者腳本管理器擴展,比如 Tampermonkey,才能安裝此腳本

您需要先安裝使用者腳本管理器擴充功能後才能安裝該腳本。

(我已經安裝了使用者腳本管理器,讓我安裝!)

你需要先安裝一款使用者樣式管理器擴展,比如 Stylus,才能安裝此樣式

你需要先安裝一款使用者樣式管理器擴展,比如 Stylus,才能安裝此樣式

你需要先安裝一款使用者樣式管理器擴展,比如 Stylus,才能安裝此樣式

你需要先安裝一款使用者樣式管理器擴展後才能安裝此樣式

你需要先安裝一款使用者樣式管理器擴展後才能安裝此樣式

你需要先安裝一款使用者樣式管理器擴展後才能安裝此樣式

(我已經安裝了使用者樣式管理器,讓我安裝!)

// ==UserScript==
// @name         Play Youtube playlist in reverse order
// @namespace    https://github.com/Dragosarus/Userscripts/
// @version      3.2
// @description  Adds button for loading the previous video in a YT playlist
// @author       Dragosarus
// @match        www.youtube.com/*
// @grant        none
// @require      http://code.jquery.com/jquery-latest.js
// ==/UserScript==

// Cookies (current session):
// pytplir_playPrevious - saves the button state between loads

/* NOTES:
 *    - Since version 2.3, due to how Youtube loads pages, @match has been expanded
 *      from www.youtube.com/watch?*list* to www.youtube.com/* in order to avoid having to refresh the page
 *      in order to run the script (and display the button). Change it back if this is not desired.
 *    - If the button is not displayed (but the script is running), do one of the following:
 *      . pause and unpause the video
 *      . reload the video via the playlist
 *      . refresh the page
 *      . press 'i' twice (i.e. enter and exit miniplayer mode).
 *    - If the button is displayed but does not work properly/consistently, increase the value of redirectWhenTimeLeft.
*/

(function() {
    'use strict';
    $(document).ready(function() {
        // Determines when to load the next video.
        // Increase these if the redirect does not work as intended (i.e. fails to override Youtube's redirect),
        // Decreasing these will let you see more of the video before it redirects, but the redirect might stop working (consistently)
        var redirectWhenTimeLeft = 0.2; // seconds before end of video
        var redirectWhenTimeLeft_miniplayer = 0.2;

        var activeColor = "rgb(64,166,255)";
        var inactiveColor = "rgb(144,144,144)";
        var circleColor = "rgb(144,144,144)";
        var ttBGColor = "rgb(100,100,100)";
        var ttTextColor = "rgb(237,240,243)";

        var player;
        var playPrevious;
        var ytdApp = $("ytd-app")[0];
        var redirectFlag = false;

        // create button
        var btn_div = document.createElement("div");
        var bg_circle = document.createElementNS("http://www.w3.org/2000/svg","circle");
        var bg_circle_anim = document.createElementNS("http://www.w3.org/2000/svg","animate");
        var arrow_up = document.createElementNS("http://www.w3.org/2000/svg","polygon");
        var arrow_down = document.createElementNS("http://www.w3.org/2000/svg","polygon");
        var btn_svg = document.createElementNS("http://www.w3.org/2000/svg","svg");
        var tt_svg = document.createElementNS("http://www.w3.org/2000/svg","svg");
        var tt_svg_fadein = document.createElementNS("http://www.w3.org/2000/svg","animate");
        var tt_svg_fadeout = document.createElementNS("http://www.w3.org/2000/svg","animate");
        var tt_rect = document.createElementNS("http://www.w3.org/2000/svg","rect");
        var tt_text = document.createElementNS("http://www.w3.org/2000/svg","text");
        var tt_div = document.createElement("div");

        bg_circle_anim.setAttribute("attributeName","fill-opacity");
        bg_circle_anim.setAttribute("values","0;0.1;0.2;0.1;0.0");
        bg_circle_anim.setAttribute("dur","0.3s");
        bg_circle_anim.setAttribute("restart","always");
        bg_circle_anim.setAttribute("repeatCount","1");
        bg_circle_anim.setAttribute("begin","indefinite");
        bg_circle_anim.setAttribute("id","pytplir_bg_circle_anim");
        bg_circle.setAttribute("cx","20");
        bg_circle.setAttribute("cy","20");
        bg_circle.setAttribute("r","20");
        bg_circle.setAttribute("fill",circleColor);
        bg_circle.setAttribute("fill-opacity","0");
        bg_circle.appendChild(bg_circle_anim);
        arrow_up.setAttribute("points","17,19 17,17 13,17 20,11 27,17 23,17 23,19");
        arrow_up.setAttribute("id","pytplir_arrow_up");
        arrow_down.setAttribute("points","17,21 17,23 13,23 20,29 27,23 23,23 23,21");
        arrow_down.setAttribute("id","pytplir_arrow_down");

        btn_svg.setAttribute("viewbox","0 0 40 40");
        btn_svg.setAttribute("xmlns","http://www.w3.org/2000/svg");
        btn_svg.setAttribute("width","40");
        btn_svg.setAttribute("height","40");
        btn_svg.setAttribute("style","cursor: pointer; margin-left: 8px;");
        btn_svg.setAttribute("id","pytplir_btn");
        btn_svg.appendChild(bg_circle);
        btn_svg.appendChild(arrow_up);
        btn_svg.appendChild(arrow_down);

        tt_rect.setAttribute("x","0");
        tt_rect.setAttribute("y","0");
        tt_rect.setAttribute("rx","2");
        tt_rect.setAttribute("ry","2");
        tt_rect.setAttribute("width","110");
        tt_rect.setAttribute("height","34");
        tt_rect.setAttribute("fill",ttBGColor);
        tt_rect.setAttribute("fill-opacity","0.9");

        tt_text.setAttribute("x","8");
        tt_text.setAttribute("y","22");
        tt_text.setAttribute("font-family","Roboto, Noto, sans-serif");
        tt_text.setAttribute("font-size","13px");
        tt_text.setAttribute("fill",ttTextColor);
        tt_text.setAttribute("style","user-select:none;");
        tt_text.innerHTML = "Autoplay order";

        tt_svg_fadein.setAttribute("attributeType","CSS");
        tt_svg_fadein.setAttribute("attributeName","opacity");
        tt_svg_fadein.setAttribute("values","0;1");
        tt_svg_fadein.setAttribute("dur","0.1s");
        tt_svg_fadein.setAttribute("restart","always");
        tt_svg_fadein.setAttribute("repeatCount","1");
        tt_svg_fadein.setAttribute("begin","indefinite");
        tt_svg_fadein.setAttribute("id","pytplir_tt_fadein");
        tt_svg_fadein.setAttribute("fill","freeze");
        tt_svg_fadeout.setAttribute("attributeType","CSS");
        tt_svg_fadeout.setAttribute("attributeName","opacity");
        tt_svg_fadeout.setAttribute("values","1;0");
        tt_svg_fadeout.setAttribute("dur","0.1s");
        tt_svg_fadeout.setAttribute("restart","always");
        tt_svg_fadeout.setAttribute("repeatCount","1");
        tt_svg_fadeout.setAttribute("begin","indefinite");
        tt_svg_fadeout.setAttribute("id","pytplir_tt_fadeout");
        tt_svg_fadeout.setAttribute("fill","freeze");
        tt_svg.setAttribute("viewbox","0 0 100 34");
        tt_svg.setAttribute("xmlns","http://www.w3.org/2000/svg");
        tt_svg.setAttribute("width","100");
        tt_svg.setAttribute("height","34");
        var tt_svg_offset = "position:absolute; top:13px; left:-32px; z-index:100; opacity:0.0;";
        tt_svg.setAttribute("style","padding-left: 10px; fill:" + ttBGColor + "; " + tt_svg_offset);
        tt_svg.setAttribute("id","pytplir_tt");
        tt_svg.appendChild(tt_rect);
        tt_svg.appendChild(tt_text);
        tt_svg.appendChild(tt_svg_fadein);
        tt_svg.appendChild(tt_svg_fadeout);
        tt_div.setAttribute("style", "position:relative; width:0; height:0;");
        tt_div.appendChild(tt_svg);

        btn_div.setAttribute("id","pytplir_div");
        btn_div.appendChild(btn_svg);
        btn_div.appendChild(tt_div);
        $(btn_svg).on("click",onButtonClick);
        $(btn_svg).on("click",function(){$(this).parent().find("#pytplir_bg_circle_anim")[0].beginElement();});
        $(btn_svg).on("mouseenter",function(){$(this).parent().find("#pytplir_tt_fadein")[0].beginElement();});
        $(btn_svg).on("mouseleave",function(){$(this).parent().find("#pytplir_tt_fadeout")[0].beginElement();});

        // remove the need to refresh the page for the script to work properly
        $("html")[0].addEventListener("yt-navigate-finish",init); // most cases

        init();

        function init() {
            // remove the need to refresh the page for the script to work properly
            withQuery("ytd-player","*",function(res) {
                res[0].addEventListener("yt-player-updated",init); // when in miniplayer mode and (playPrevious is false or shuffle is on)
            });

            removeButton(); // try to ensure button is (re-)added properly
            playPrevious = getCookie("pytplir_playPrevious");
            if (playPrevious === "") { // cookie has not been set yet
                playPrevious = false; // inital state
                setCookie("pytplir_playPrevious",playPrevious);
            }
            setTimeout(addButton, 500);
            setTimeout(start, 500);
        }

        function onButtonClick() { // toggle
            playPrevious = !playPrevious;
            setCookie("pytplir_playPrevious",playPrevious);
            updateButtonState();
        }

        function addButton() {
            withQuery(".ytd-playlist-panel-renderer > div[id=top-level-buttons]", "*", function(res) {
                res.each(function() {
                    if (!$(this).filter(":has(#pytplir_div)").length) {
                        this.appendChild($(btn_div).clone(true)[0]);
                        updateButtonState();
                    }
                });
            });
        }

        function updateButtonState() {
            if (playPrevious) { // play previous video
                $("polygon[id=pytplir_arrow_up]").each(function() {
                    this.setAttribute("style","fill:"+activeColor);
                });
                $("polygon[id=pytplir_arrow_down]").each(function() {
                    this.setAttribute("style","fill:"+inactiveColor);
                });
            } else { // play next video
                $("polygon[id=pytplir_arrow_up]").each(function() {
                    this.setAttribute("style","fill:"+inactiveColor);
                });
                $("polygon[id=pytplir_arrow_down]").each(function() {
                    this.setAttribute("style","fill:"+activeColor);
                });
            }
        }

        function removeButton() {
            $("div[id=pytplir_div]").each(function(){
                this.parentNode.removeChild(this);
            });
        }

        function start() {
            withQuery(".html5-main-video", ":visible", function(res) {
                player = res[0];
                player.addEventListener("timeupdate",checkTime);
                player.addEventListener("play", addButton); // ensure button is added
            });
        }

        function withQuery(query,filter="*", onSuccess = function(r){}) {
            var res = $(query).filter(filter);
            if (res.length) { // >= 1 result
                onSuccess(res);
                return res;
            } else { // not loaded yet => retry
                setTimeout(function(){withQuery(query);}, 100);
            }
        }

        function checkTime() {
            if (!$("#pytplir_div").length) {return;} // button not loaded

            var timeLeft = player.duration - player.currentTime;
            var videoPlayer = $(".html5-video-player")[0];
            var shuffle = strToBool($("path[d='M10.59 9.17L5.41 4 4 5.41l5.17 5.17 1.42-1.41zM14.5 4l2.04 2.04L4 18.59 5.41 20 17.96 7.46 20 9.5V4h-5.5zm.33 9.41l-1.41 1.41 3.13 3.13L14.5 20H20v-5.5l-2.04 2.04-3.13-3.13z']").filter(":visible").parents("button[aria-pressed]")[0].attributes["aria-pressed"].nodeValue);
            try {videoPlayer.classList.contains("ad-showing");}
            catch (TypeError) { // video player undefined
            	return;
            }

            var redirectTime;
            if (ytdApp.hasAttribute("miniplayer-active_")) {
                redirectTime = redirectWhenTimeLeft_miniplayer;
            } else {
                redirectTime = redirectWhenTimeLeft;
            }

            if (playPrevious && timeLeft < redirectTime && !redirectFlag && !player.hasAttribute("loop") && !shuffle && !videoPlayer.classList.contains("ad-showing")) {
                // attempt to prevent the default redirect from triggering
                player.pause();
                player.currentTime -= 2;

                redirectFlag = true;
                redirect();
                setTimeout(function() {redirectFlag = false;}, 1000);
            }
        }

        function redirect() {
            var previousURL = getPreviousURL();
            if (previousURL) {
                previousURL.click();
            }
        }

        function getPreviousURL(){ // returns <a> element
            var elem;
            if (ytdApp.hasAttribute("miniplayer-active_")) { // avoid being forced out of miniplayer mode on video load
                elem = $("div.miniplayer").find("ytd-playlist-panel-video-renderer[selected]").prev();
                while (!elem.find("#unplayableText").prop("hidden")) { // while unplayable (e.g. private) video is selected
                    elem = elem.prev();
                }
                return elem.children()[0];
            } else {
                elem = $("#content").find("ytd-playlist-panel-video-renderer[selected]").prev();
                while (!elem.find("#unplayableText").prop("hidden")) { // while unplayable (e.g. private) video is selected
                    elem = elem.prev();
                }
                return elem.children()[0];
            }
        }

        function strToBool(str) {
            return str.toLowerCase() == "true" ? true : false;
        }

        // 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 strToBool(x);
                }
            }
            return "";
        }
    });
})();