ember-file-upload

controllers.application.js

import Ember from 'ember';

export default Ember.Controller.extend({
  appName: 'ember-file-upload',
  
  actions: {
		addPhoto(file) {
	    file.readAsDataURL().then((src) => {
        this.set('photos', (this.get('photos') || []).slice().concat({ src }));
      });
    }
  }
});

templates.application.hbs

{{#file-dropzone name='photos'}}
  {{#each photos as |photo|}}
    <img src={{photo.src}}/>
  {{/each}}

  {{#file-upload name='photos' multiple=true onfileadd=(action 'addPhoto')}}
    + Add photo
  {{/file-upload}}
{{/file-dropzone}}

twiddle.json

{
  "version": "0.12.1",
  "EmberENV": {
    "FEATURES": {}
  },
  "options": {
    "use_pods": false,
    "enable-testing": false
  },
  "dependencies": {
    "jquery": "https://cdnjs.cloudflare.com/ajax/libs/jquery/1.11.3/jquery.js",
    "ember": "2.12.0",
    "ember-template-compiler": "2.12.0",
    "ember-testing": "2.12.0"
  },
  "addons": {
    "ember-data": "2.12.1",
    "ember-file-upload": "2.1.2"
  }
}