XMLHttpRequest and BLOBs

The one thing you should remember when dealing with XMLHttpRequest on NW.js applications is that local files, called through the file:// or app:// protocols, return 0 as the HTTP response.

var xhr = new XMLHttpRequest(), blob;
xhr.open('GET', 'myBlob.jpg', true);
xhr.responseType = 'blob';
xhr.addEventListener('load', function () {
  if (xhr.status !== 200) return;
  blob = xhr.response;
  // Do something with blob
}, false);
xhr.send();

In the preceding example, we try to get a BLOB ( which, in our case, is an image), but the code will stop when checking for xhr.status !== 200 as the returned status for local files will indeed be 0. I take this opportunity to show you how to store BLOBs in an IndexedDB object store:

var xhr = new XMLHttpRequest(), blob;
xhr.open('GET', 'maggieAvatar.jpg', true);
xhr.responseType = 'blob';
xhr.addEventListener('load', function () {
  maggieAvatar = xhr...