Ember.js -- Persist Record on Browser Close

I'd like to persist a record when the user exits my app. I have the following code in my controller:

  addUnloadEvent: function () {
    let _this = this;
    Ember.$(window).unload(function() {
      console.log("ATTEMPTING TO PERSIST RECORD");
      let record = _this.get('model');
      console.log("RECORD: "+record);
      record.save();
    });

  }.on('init'),

The console logs the record when I close the app, but no server request is made. Any help is appreciated.