cordova image to base64

image2Base64.js

function readData(imageURI) {
  function gotFileEntry(fileEntry) {
      console.log("got image file entry: " + fileEntry.fullPath);
      fileEntry.file(function (file) {

          var reader = new FileReader();
          reader.onloadend = function (evt) {
              console.log(evt.target.result);
          };
          //reader.readAsText(file);
          reader.readAsDataURL(file);
      }, function (err) {
          console.log(err);
      });
  }
  function failSystem(err) {
      console.log(err);
  }

  $ionicPlatform.ready(function () {
      window.resolveLocalFileSystemURI(imageURI, gotFileEntry, failSystem);
  });
}