Example of custom pager script for MangaWindow (original site's scripts should be disabled)

autopatchwork_mangawindow.js

// ==UserScript==
// @description MangaWindow reader service script for AutoPatchWork mod.
// @include https://mangawindow.com/*
// ==/UserScript==

if (window.opera && ~location.pathname.indexOf('chapter')) {
    // NSL error in Opera 12 caused by some random change in the site's code :( 
/*  // Additional CSS fixes:
    .body-chapter .chapter-nav select, .body-chapter .chapter-nav select, .body-chapter .chapter-nav .nav-chas select { 
        color: #000;
    }
    .page-num {display:none}
*/
    window.opera.addEventListener('BeforeScript', function(userJSEvent) {
        userJSEvent.preventDefault();
    }, false);
    gotop = function(){};
}

(function(){
var on, off, trigger;
var base_url = 'https://mangawindow.com/chapter/',
    current_index = 1,
    current_chapter = null,
    current_chapter_n = 0,
    is_new_chapter = false,
    next_chapter = null,
    img_array = [],
    null_chapter = null,
    img_array_len = 0;

function copyTitleToClipboard() {
    try {
        var title = document.querySelector('.nav-title > a');
        //title.textContent = title.textContent.replace(/ Man[gh][uw]?a/i,'');
        if (!title) return;
        var range = document.createRange();
        range.selectNodeContents(title);
        var sel = window.getSelection();
        sel.removeAllRanges();
        sel.addRange(range);
        document.execCommand('copy');
    } catch (err) {}
}

function currentChapterLink(index) {
    return current_chapter;
}

function updateChapterVariables(nodes, url, initial) {
    var script_cue = 'var images = {',
        scripts = nodes.querySelectorAll('script');
    //serach all embedded scripts for matching array and chapter data
    for (var text = '', i = 0; i < scripts.length; i++) {
        if (scripts[i].text.indexOf(script_cue) !== -1) {
            text = scripts[i].text;
            is_new_chapter = false;
            img_array = text.replace(/"\d+":/g,'').replace(/"/g,'').match(/var images\s*=\s*{([^}]+)}/)[1].split(',');
            img_array_len = img_array.length;
            current_index = 1;
            current_chapter = url;
            next_chapter = text.match(/var nextCha\s*=\s*[^\=]+uniqueId.:(\d+)/);
            next_chapter = next_chapter ? next_chapter[1] : '';
            current_chapter_n = text.match(/var prevCha\s*=\s*[^\=]+volcha":"[^\d"]+(\d+)/);
            if (current_chapter_n && current_chapter_n[1]) {
                current_chapter_n = parseInt(current_chapter_n[1], 10) + 1;
            } else {
                current_chapter_n = text.match(/var nextCha\s*=\s*[^\=]+"volcha":"[^\d"]+(\d+)/);
                if (current_chapter_n && current_chapter_n[1]) {
                    current_chapter_n = parseInt(current_chapter_n[1], 10) - 1;
                } else {
                    current_chapter_n = 1;
                }
            }
            if (initial) current_index = img_array_len;
            break;
        }
    }
}

function generateBody(index, url) {
    return  '<div id=\"viewer\"><div class="item"><img style=\"max-width:1100px;display:block;\" src=\"' + img_array[index-1] + '\" /></div></div>';
}

function generateTitle(page, title, chapter, volume) {
    return (chapter ? (' ch.'  + chapter + ' ') : '') + 'p.' + page + ' of ' + title;
}

function terminateAPW(event) {
    console.log('[APW; mangawindow]', 'terminated');
    trigger('terminated', { message: 'Last chapter reached'});
    off('request');
    off('load');
    if (!event) return;
    event.preventDefault();
    event.stopPropagation();
}

function handleNewPageLink(event) {
    is_new_chapter = false;
    current_index += 1;
    if (!img_array_len) return;
    if (current_index <= img_array_len) {
        event.detail.norequest = true;
    } else {
        is_new_chapter = true;
        if (isChapter(next_chapter)) event.detail.link = base_url + next_chapter + '/';
        else { event.detail.link = ''; terminateAPW(event); }
    }
}

function handleNewPageLoad(event) {
    if (is_new_chapter) {
        updateChapterVariables(event.detail.htmlDoc, event.detail.url, false);
    } else {
        event.detail.url = currentChapterLink(current_index);
    }
    event.detail.htmlDoc.body.innerHTML = img_array[current_index-1] ? generateBody(current_index, event.detail.url) : null;
    var tl = event.detail.htmlDoc.querySelector('title');
    if (!tl) {
        tl = document.createElement('title');
        event.detail.htmlDoc.head.appendChild(tl);
    }
    tl.textContent =  generateTitle(current_index, document.querySelector('.nav-title a').textContent, current_chapter_n);
}

function isChapter(chapter) {
    return chapter && chapter.length && chapter !== null_chapter && (chapter.indexOf('javascript:')  === -1);
}

function initChapter() {
    var container = document.querySelector('#viewer');
    for (var i = 0; i < img_array_len; i++) {
        var img = document.createElement('img'),
            div = document.createElement('div');
        div.className = "item";
        img.src = img_array[i];
        img.style = "max-width:1100px;display:block;";
        div.appendChild(img);
        container.appendChild(div);
    }
    var tl = document.querySelector('title');
    if (!tl) {
        tl = document.createElement('title');
        document.head.appendChild(tl);
    }
    tl.textContent =  generateTitle(current_index, document.querySelector('.nav-title a').textContent, current_chapter_n);
}

document.addEventListener('AutoPatchWork.ready', function() {
    console.log('[APW; mangawindow]', 'helper script loaded');
    trigger = window.AutoPatchWorked.trigger;
    on = window.AutoPatchWorked.on;
    off = window.AutoPatchWorked.off;
    if (!document.querySelectorAll('#viewer').length) {
        // block native autopager sript `latest.mod.js` for this to work
        // also this to prevent any jitter:
        if (window.opera) {
            window.opera.addEventListener('BeforeScript', function(e) {
                if (~userJSEvent.element.src.indexOf('anycg')) e.preventDefault();
            }, false);
            window.scrollBy = window.scrollTo = function(){};
        }
        trigger('siteinfo', {
            siteinfo : {
                url: '^https://mangawindow\\.com/latest',
                pageElement: '.item.col-24',
                nextMask: 'https://mangawindow.com/latest?page=|1|',
                forceAddressChange: true // my default setting is enabled, this reverts it
            }
        });
    } else {
        on('request', handleNewPageLink);
        on('load', handleNewPageLoad);
        updateChapterVariables(document, location.href, true);
        if (!!window.opera) initChapter();
        if (!isChapter(next_chapter)) return;
        trigger('siteinfo', {
            siteinfo : {
                url: '^https://mangawindow\\.com/chapter',
                pageElement: 'id(\"viewer\")/*',
                nextLink: '//a',
                disableSeparator: true,
                cssPatch: ".item>img {min-height:500px;}"
            }
        });
    }
}, false);

//if (typeof browser !== 'undefined')
    document.addEventListener('DOMContentLoaded', function() {
        copyTitleToClipboard();
        //window.AutoPatchWorked.trigger('ready');
    }, false);
}());