E-Hentai Load More Thumbnails

On an e-hentai gallery page, click "Load more" next to the page numbers and enter how many pages' worth of additional thumbnails you want to load onto the current page.

As of 2020-02-05. See the latest version.

// ==UserScript==
// @name        E-Hentai Load More Thumbnails
// @namespace   e-hentai.org
// @description On an e-hentai gallery page, click "Load more" next to the page numbers and enter how many pages' worth of additional thumbnails you want to load onto the current page.
// @match       *://*.exhentai.org/g/*
// @match       *://*.e-hentai.org/g/*
// @version     0.2.0
// @grant       none
// ==/UserScript==

console.log('Hi load more thumbs');

const MAX_PAGES = 20;
const START_PAGES = 0;
const DEFAULT_PAGES = 2;
var last_loaded = 0;
var base_url = '';

var container_div = document.querySelector('#gdt');
var c_div = document.querySelector('#gdt .c');
var top_row = document.querySelector('.ptt tr');
var bottom_row = document.querySelector('.ptb tr');
var new_td = document.createElement('td');
var a = document.createElement('a');
a.onclick = "return false";
a.innerHTML = 'Load more';
new_td.appendChild(a);
new_td.style.width = '72px';
new_td2 = new_td.cloneNode(true);
new_td.onclick = new_td2.onclick = pop_up;

top_row.appendChild(new_td);
bottom_row.appendChild(new_td2);

var m = document.location.href.match(/^([^?]+)(?:\??.*p=(\d+))?/);
if (m) {
	base_url = m[1];
	if (m[2]) {
		last_loaded = Math.max(last_loaded, m[2]);
	}
}

var page_links = Array.from(document.querySelectorAll('.ptt a'));
const last_page = Math.max.apply(null, page_links.map((el) => {
		var m = el.href && el.href.match(/p=(\d+)/);
		return parseInt(m && m[1]);
	})
	.filter((num) => num));

START_PAGES > 0 && start_load(START_PAGES);

function pop_up() {
	if (last_loaded >= last_page) {
		alert('No more pages to load');
		console.log('No more pages to load');
	} else {
		var desired_pages = parseInt(prompt('Load how many pages', localStorage.getItem('eh_desired_pages') || DEFAULT_PAGES));
		if (desired_pages > 0) {
			localStorage.setItem('eh_desired_pages', desired_pages);
			start_load(desired_pages);
		}
	}
}

function start_load(desired_pages) {
	if (last_loaded >= last_page) {
		console.log('No more pages to load');
		return;
	}
	var number_wanted = Math.min(desired_pages, MAX_PAGES);
	var end = Math.min(last_loaded + number_wanted, last_page);

	if (!document.querySelector('#marker' + (last_loaded + 1))) {
		add_marker(last_loaded + 1);
	}
	for (var i = last_loaded + 1; i <= end; i++) {
		var marker_div = add_marker(i + 1);
		var url = base_url + '?p=' + i;
		console.log('loading thumbs from', url)
		var oReq = new XMLHttpRequest();
		oReq.addEventListener('load', page_load(marker_div));
		oReq.open('GET', url);
		oReq.responseType = 'document';
		oReq.send();
		last_loaded = i;
	}
    adjust_page_links();
}

function add_marker(i) {
	var marker_div = document.createElement('div');
	marker_div.innerHTML = 'Page ' + i;
	marker_div.id = 'marker' + i;
	marker_div.style.clear = 'both';
	container_div.appendChild(marker_div);
	return marker_div;
}

function page_load(marker) {
	return function() {
		console.log(marker.id, 'response', this.response);
		const thumb_divs = Array.from(this.response.querySelectorAll('.gdtl, .gdtm, .gdts'));
		thumb_divs.forEach((el) => {
			container_div.insertBefore(el, marker);
		});
        increase_image_number(thumb_divs.length);
	}
}

function increase_image_number(num) {
    let image_count_p = document.querySelector('.gpc');
    image_count_p.textContent = image_count_p.textContent.replace(/Showing (\d+) - (\d+)/i, (m, p1, p2) => `Showing ${p1} - ${parseInt(p2) + num}`);
}

function adjust_page_links() {
    let current_page_tds = document.querySelectorAll('.ptds');
    let m = current_page_tds[0].textContent.trim().match(/(\d+)(?: - (\d+))?/);
    const current = parseInt(m && m[1]);
    const old_last_loaded = parseInt(m && m[2]) || current;
    for (let td of current_page_tds) {
        td.style.width = 'auto';
        td.style.padding = '0px 6px';
        let a = td.firstElementChild;
        a.textContent = `${current} - ${last_loaded + 1}`;
    }
    let gtbs = document.querySelectorAll('.gtb');
    for (let gtb of gtbs) {
        let tds = gtb.querySelectorAll('td');
        let prev_num = 0;
        let increment = last_loaded - old_last_loaded + 1;
        for (let td of tds) {
            let m = td.textContent.trim().match(/^\d+$/);
            let num = m && parseInt(m[0]);
            if (num > current && num < last_page + 1) {
                let new_num = num + increment;
                let a = td.firstElementChild;
                if (new_num < last_page + 1) {
                    a.textContent = new_num;
                    a.href = a.href.replace(/\?p=\d+/, `?p=${new_num - 1}`);
                } else {
                    td.parentNode.removeChild(td);
                }
            } else if (td.textContent.trim() === '...' && prev_num > current) {
                if (prev_num + increment >= last_page) {
                    td.parentNode.removeChild(td);
                }
            }
            prev_num = num;
        }
    }
}