title: Get Onload of a XHR call
body: <p>The goal or aim is to put a dummy url untill the actual xhr call loads.The original call is S3.getsignedurl() which returns a url and that url is called in respective html tags; i.e. Image in , PDF files in .
  I need to find out when that url is loaded and then switch the images from the temporary to the actual one. Any ideas?</p>