Convert URL to File or Blob for FileReader.readAsDataURL

Question

Reference: FileReader.readAsDataURL

Considering the following example:

function previewFile(file) {    var reader  = new FileReader();    reader.onloadend = function () {     console.log(reader.result);   }   reader.readAsDataURL(file); } 

It states:

instanceOfFileReader.readAsDataURL(blob);

blob: The Blob or File from which to read.

1. How can a local file URL like: 'file:///C:/path-to/root.png' be passed to the readAsDataURL()

2. Is FileReader() available in a Firefox Addon?

Answer 1

To convert a URL to a Blob for FileReader.readAsDataURL() do this:

var request = new XMLHttpRequest(); request.open('GET', MY_URL, true); request.responseType = 'blob'; request.onload = function() {     var reader = new FileReader();     reader.readAsDataURL(request.response);     reader.onload =  function(e){         console.log('DataURL:', e.target.result);     }; }; request.send();