ImMrStealyBook.js

/* A book page URL is like http://reader.vlebooks.com/reader/sessionid_<ID>/page/MTA3My84NTE4LzQvMA==
 * The page of a book is from MTA3My84NTE4LzQvMA== this is simply a base64 encoded string.
 * Decoded it becomes something like 1073/8518/4/0
 * That is <Page>/<Some>/<Other>/<Ids>
 * For educational purposes only.
 */ 

// Example call stealBook(4, "23672386824842", "/1337/1/2")
function stealBook(bookPageCount, session_id, bookId) {
    $.getScript('https://cdnjs.cloudflare.com/ajax/libs/jszip/2.6.1/jszip.js', function()
    {
      	let bookPages = new JSZip();
        let donePages = 0;
        for (let page=1; page<=bookPageCount; page++) {
            page_id = btoa(page+bookId);
            page_url = "http://reader.vlebooks.com/reader/sessionid_"+session_id+"/page/"+page_id;
            let request = new XMLHttpRequest();
            request.open('GET', page_url, true);
            request.responseType = 'blob';
            request.onload = function() {
                if (request.response === null) {
                    donePages++;
                    return;
                }
                console.log(request.response);
                let reader = new FileReader();
                reader.readAsDataURL(request.response);
                reader.onload =  function(e){
                    console.log(page_url);
                    base64 = e.target.result;
                    let index = base64.indexOf(",");
                    if (index !== -1) {
                        base64 = base64.substring(index + 1, base64.length);
                    }
                    bookPages.folder("pages").file("page" + page + ".jpg", base64, {base64: true});
                    donePages++;
                    if (donePages == bookPageCount) 
                        location.href= "data:application/zip;base64,"+bookPages.generate();
                };
            };
            request.send();
        }
    });
}