championscans_JSZip_powered_download_button.user.js

// ==UserScript==
// @name         championscans download button
// @version      0.3
// @description  Add a javascript powered download button
// @match        https://reader.championscans.com/read/*
// @require      https://stuk.github.io/jszip/dist/jszip.js
// @require      https://stuk.github.io/jszip-utils/dist/jszip-utils.js
// @require      https://stuk.github.io/jszip/vendor/FileSaver.js
// @grant        none
// ==/UserScript==
// This here is the userscript version, tested on tampermonkey version 2.9.1 (Super old version which is the last open sourced version)
// This is some boilerplate stuff from the example https://stuk.github.io/jszip/documentation/examples/downloader.html
var Promise = window.Promise;
if (!Promise) {
    Promise = JSZip.external.Promise;
}
/**
 * Fetch the content and return the associated promise.
 * @param {String} url the url of the content to fetch.
 * @return {Promise} the promise containing the data.
 */
function urlToPromise(url) {
    return new Promise(function(resolve, reject) {
        JSZipUtils.getBinaryContent(url, function (err, data) {
            if(err) {
                reject(err);
            } else {
                resolve(data);
            }
        });
    });
}
// Create the button. it has the same content as the original so it would look more or less the same.
DL_button = document.createElement('div');
DL_button.innerHTML = '<a id="CS-DL-BUN" class="br-tab" title="Download""><i aria-hidden="true" class="br-i-download"></i></a>';
DL_button = DL_button.firstChild;
DL_downloading = false;
// The download function
DL_button_func = function(){
    fetch(window.location.href+'/manifest.json').then(
        (res) => {return res.json()}
    ).then(
        (json) => {
            var zip = new JSZip();
            // Find every page
            // Reason for using an element will be explain in DL_button_inject
            for (img of json.readingOrder) {
            	zip.file(img.href.split('/').pop(), urlToPromise(img.href), {binary:true});
            }
            // When everything has been downloaded, we can trigger the dl
            zip.generateAsync({type:"blob"}, function updateCallback(metadata) {
                var msg = "progression : " + metadata.percent.toFixed(2) + " %";
                console.log(msg);
            }).then(function callback(blob) {
                filename = "[Champion_Scans]"+json.metadata.belongsTo.series.name.replace(' ','_')+"_c"+json.metadata.belongsTo.series.position.padStart(2,0)+".zip";
                // see FileSaver.js
                saveAs(blob, filename);
                console.log("done !");
                DL_downloading = false;
            }, function (e) {
                alert(e);
                DL_downloading = false;
            });
        }
    )
    return false;
}
DL_button_prefunc = function(){
    // Prevent it from running again when it's still running
    if (DL_downloading === true){
        alert('Already downloading!')
    	return
    }
    DL_downloading = true;
    DL_button_func();
}
DL_button.addEventListener( "click", DL_button_prefunc );

DL_button_exist_check = function(){
    if(!document.getElementById("CS-DL-BUN")){
    	setTimeout(()=>{document.getElementsByClassName('br-cmenu')[0].getElementsByTagName('nav')[0].prepend(DL_button)}, 1000);
    };
};

setInterval(DL_button_exist_check, 250);