try to take over the world!
当前为 2021-08-07 提交的版本，查看最新版本。
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// ==UserScript==
// @name         预加载下一章/页，方向键上/下一章
// @namespace    http://tampermonkey.net/
// @version      0.3
// @description  try to take over the world!
// @author       wodexianghua
// @match        http://*/*
// @match        https://*/*
// @grant        none
// ==/UserScript==

(function () {
    'use strict';
    var shang = false;
    var xia = false;
    var searchText_now = [];
    var found_pre_now;
    var found_next_now;
    var iscanfenye = true;
    var searchText = {
        pre: ["上一章", "上一页", "pre", "<"],
        next: ["下一章", "下一页", "next", ">"]
    }

    document.addEventListener('keydown', function (event) {
        if (document.activeElement.nodeName != 'BODY') return;
        else if (document.activeElement.nodeName == 'BODY' && !iscanfenye) {
            return;
        }

        if (event.keyCode == 37) {
            shang = true;
        } else if (event.keyCode == 39) {
            xia = true;
        }

        //是否按下左右键
        if (shang || xia) {
            if (shang) {
                if (found_pre_now != undefined && document.contains(found_pre_now) && isincludes(found_pre_now, searchText.pre)) {
                    shang = false;
                    found_pre_now.click();
                    return;
                } else {
                    searchText_now = searchText.pre;
                }
            } else {
                if (found_next_now != undefined && document.contains(found_next_now) && isincludes(found_next_now, searchText.next)) {
                    xia = false;
                    found_next_now.click();
                    return;
                } else {
                    searchText_now = searchText.next;
                }
            }
            let found = getpreornextelement(searchText_now);
            if (found != undefined) found.click();
            shang = false;
            xia = false;
        }
    });

    //如果有视频在播放，禁用左右键翻页
    let video = document.querySelector('video');
    if (video != null) {
        video.addEventListener("play", function () {
            iscanfenye = false;
        });
        video.addEventListener("pause", function () {
            iscanfenye = true;
        });
    }

    setTimeout(() => {
        foundnextpage();
        foundpreviouspage();
    }, 8000);

    function foundpreviouspage() {
        found_pre_now = getpreornextelement(searchText.pre);
    }

    //预加载下一页
    function foundnextpage() {
        found_next_now = getpreornextelement(searchText.next);

        //如果没找到或者href是javascript的话就退出
        if (found_next_now == undefined) {
            return;
        } else if ((found_next_now != "没找到") && found_next_now.getAttribute('href').includes("javascript")) {
            return;
        }

        let xiaurl = found_next_now.getAttribute('href');
        if (!xiaurl.includes(document.domain)) {
            var ishttps = 'https:' == document.location.protocol ? true : false;
            if (ishttps) {
                xiaurl = 'https://' + xiaurl;
            } else {
                xiaurl = 'http://' + xiaurl;
            }
        }
        var head = document.querySelector('head');
        head.insertAdjacentHTML('beforeend', '<link rel="prefetch" href="' + xiaurl + '" />');
        return;
    }

    /**
     * @param {string[]} searchTextarry
     * @return {HTMLAnchorElement} 
     */
    function getpreornextelement(searchTextarry) {
        for (const iterator of searchTextarry) {
            if (document.body.innerText.includes(iterator)) {
                let aTags = document.getElementsByTagName("a");

                for (const iterator of searchTextarry) {
                    for (let i = 0; i < aTags.length; i++) {
                        if (aTags[i].textContent.includes(iterator) || (aTags[i].className == "next" | aTags[i].className == "n" | aTags[i].className == "pre" | aTags[i].className == "p")) {
                            let found = aTags[i];
                            return found;
                        }
                    }
                }
            }
        }
        return undefined;
    }

    /**
     * @param {string[]} searchTextarry
     * @param {string} Text
     */
    function isincludes(Text, searchTextarry) {
        for (const iterator of searchTextarry) {
            if (Text.textContent.includes(iterator)) {
                return true;
            }
        }
        return false;
    }
    // Your code here...
})();