Panda Infinite Scroll

Infinite scrolling for galleries in e-hentai and exhentai
Versão de: 14/09/2019. Veja: a última versão.
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// ==UserScript==
// @name          Panda Infinite Scroll
// @description	  Infinite scrolling for galleries in e-hentai and exhentai
// @namespace     https://gist.github.com/ytjchan
// @author        ytjchan
// @version       1.0.0
// @include       *://e-hentai.org/*
// @include       *://exhentai.org/*
// @exclude       *://e-hentai.org/g/*
// @exclude       *://e-hentai.org/s/*
// @exclude       *://exhentai.org/g/*
// @exclude       *://exhentai.org/s/*
// ==/UserScript==

// Current page (0-indexed)
let url = new URL(window.location);
if (url.pathname.includes("tag") && isNaN(url.pathname.split("/").slice(-1)[0]))
    url.href += "/0";
url.setPage = (url.pathname.includes("tag"))? 
    page => url.href = url.href.replace(/\/[^\/]*$/, "/"+page) :
    page => url.searchParams.set("page", page);
let currentPage = (url.pathname.includes("tag"))? 
    (parseInt(url.pathname.split("/").slice(-1)[0]) || 0) :
    (parseInt(url.searchParams.get("page")) || 0);
// Restore current page in case of page back
if (document.getElementsByClassName("page-anchor").length !== 0)
    currentPage = Math.max(...Array.from(document.getElementsByClassName("page-anchor")).map(el => parseInt(el.getAttribute("data-page"))));

// Max page
let pageBtns = document.querySelectorAll(".ptt td");
let maxPage = parseInt(pageBtns[pageBtns.length-2].textContent) - 1;

// Detect if bottom of page reached
let observer = new IntersectionObserver(fetchNextPage, { threshold: 1.0 });
observer.observe(document.querySelector(".ptb"));

// Alert area
let flex = document.createElement("div");
flex.setAttribute("style", "display: flex;flex-direction: column;align-items: flex-end;position: fixed;top: 0;right: 0;z-index: 10;");
document.getElementsByTagName("body")[0].appendChild(flex);
createScrollAlert(currentPage);

let inProcess = false;
function fetchNextPage() {
    if (currentPage >= maxPage) {
        observer.disconnect();
        createAlert("Last page reached", 5000, "#0FF");
        return;
    }
    
    if (inProcess) return;
    inProcess = true;

    url.setPage(++currentPage);
    fetch(url.href)
    .then(res => res.text())
    .then(html => {
        let parent = document.querySelector(".gl1t, .itg tr").parentNode;
        let dummy = document.createElement("html");
        dummy.innerHTML = html;
        parent.innerHTML += Array.from(dummy.querySelectorAll(".gl1t, .itg tr")).reduce((prev, el, i) => {
            if (i === 0) {
                el.classList.add("page-anchor");
                el.setAttribute("data-page", currentPage);
            }
            return prev += el.outerHTML;
        }, "");
        createScrollAlert(currentPage);
        inProcess = false;
    })
    .catch(e => createAlert(e, 5000, "#F00"));
}

function createAlert(msg, timeout, bgColor = "#EEE") {
    let div = document.createElement("div");
    div.textContent = msg;
    div.setAttribute("style", "padding: 0.5em;margin-bottom: 0.1em;font-size: 1.25em;background-color: "+bgColor+";color: #000");
    flex.appendChild(div);
    setTimeout(()=>div.remove(), timeout);
    return div;
}

function scrollToPage(page) {
    if (page > currentPage) {
        alert("Page not loaded yet");
        return;
    }
    try {
        document.querySelector(".page-anchor[data-page='"+page+"']").scrollIntoView(); 
    } catch (e) { // page anchor does not exist
        document.documentElement.scrollTop = 0;
    }
}

 // display clickable page alert as 1-indexed
function createScrollAlert(page) {
    createAlert((page+1)+" / "+(maxPage+1), 5000, "#0F0")
        .addEventListener("click", scrollToPage.bind(null, page)); // display as 1-indexed
}