Download a CSV file in EmberJs

I have tried a myriad of different function calls, but can't seem to figure out how to trigger a download for a CSV in EmberJs.

Here is my latest code:

let endpoint = '/api/foo/';
let options = {
    url: endpoint,
    type: 'POST',
    data: {},
    dataType: 'text'
};
return new Ember.RSVP.Promise((resolve, reject) => {
  options.success = function(result) {
      var uri = 'data:application/csv;charset=UTF-8,' + encodeURIComponent(result);
      window.open(uri, 'foo.csv');
  };
  options.error = (xhr, errorThrown) => {
    console.log('error');
    // return Ember.run(null, reject, this.didError(xhr, xhr.status, xhr.responseJSON, 1));
  };
  Ember.$.ajax(options);
});

This code doesn't raise any server or client side errors. It's getting a 200 response. No javascript errors, and doesn't console log anything, so I know it's not hitting the error block. But... it won't trigger the file download on the client. Does anyone know what is missing?

Thanks in advance.