gistfile1.js

handleFile: function(file) {

  if (file.size / 1000000 > 150) {
    var err = "We only support files up to 150 MB";
    alert(err);
    ...
  }

  var that = this;
  $.when(this.upload(file)).pipe(this.getSharedUrl).
    done(function(response) {
      that.renderResponse(response);
      that.postResponse && that.postResponse(response);
      that.toggleLoadingIcon();
    }).
    fail(function(xhr) {
      var err;
      if (xhr.status == 403) {
        err = 'Your Dropbox account seems to be not connected. Please connect it!';
      }
      else {
        err = 'Transfer to server not successful. Please check your internet connection or contact our support team.';
      }
      alert(err);
      ...
    });
},