$(document).ready(function(){ $('#prepare_sub').click(function(e){ e.preventDefault(); var fi = document.getElementById("userfile"); var file = fi.files[0];; if (!(file)) { return; } $("#prepare_sub").prop("disabled",true).addClass("running"); if (JSZip.support.blob) { // Check if Browser supports ZIP var zip = new JSZip(); //add all files to zip addFileToZip(file); function addFileToZip(n) { var arrayBuffer; var fileReader = new FileReader(); fileReader.onloadend = function() { arrayBuffer = this.result; let chker = partof(arrayBuffer,4096); if (chker.toUpperCase().includes(' cb.checked); boxes.forEach(cb => cb.checked = !allChecked); }