batchDownload

batch_downloading.js

// Required plugins
// - https://github.com/eligrey/FileSaver.js
// - https://github.com/Stuk/jszip

// feature-detect against window.FormData, window.Blob and window.ArrayBuffer
var isSupported = !!(window.FormData && window.Blob && window.ArrayBuffer);

var downloadFile = function (url) {
  var xhr = new XMLHttpRequest(),
      deferred = new $.Deferred();

  xhr.addEventListener('load', function() {
    deferred.resolve(xhr);
  });

  xhr.open('GET', url, true);
  xhr.responseType = 'arraybuffer';
  xhr.send();

  return deferred.promise()
}

var batchDownload = function(urlList) {
  var zip = new JSZip(),
      deferreds = [];

  for (var i = 0; i < urlList.length; i += 1) {
    var deferred = (function(index) {
      return downloadFile(urlList[index]).done(function(xhr) {
        filename = 'file' + index + '.png'
        zip.file(filename, xhr.response)
      })
    })(i)

    deferreds.push(deferred);
  }

  $.when.apply($, deferreds).done(function() {
    saveAs(zip.generate({ type: 'blob' }), 'example.zip');
  });
};

$(function() {
  $('#batch_download').on('click', function(event) {
    event.preventDefault();
    batchDownload('http://...', 'http://...');
  });
});