New Twiddle

application.controller.js

import Ember from 'ember';

export default Ember.Controller.extend({
  appName:'Ember Twiddle'
});

application.template.hbs

<h1>Welcome to {{appName}}</h1>
<br>
<br>
{{outlet}}
<hr/>
{{#link-to 'other'}}Link to other route but from application template{{/link-to}}
<br>
<br>

form.controller.js

import Ember from 'ember';

export default Ember.Controller.extend({
  userHasEnteredData: true
});

form.route.js

import Ember from 'ember';

export default Ember.Route.extend({
  actions: {
    willTransition(transition) {
      console.log('will transition hook');
			if (this.controller.get('userHasEnteredData')) {      
        transition.abort();
      }
    }
  }
});

form.template.hbs

This is form route.<br/>
{{#link-to 'other'}}Link to other route{{/link-to}}

router.js

import Ember from 'ember';
import config from './config/environment';

var Router = Ember.Router.extend({
  location: config.locationType
});

Router.map(function() {
  this.route('form', { path: '/' });
  this.route('other');
});

export default Router;

twiddle.json

{
  "version": "0.4.16",
  "EmberENV": {
    "FEATURES": {}
  },
  "dependencies": {
    "jquery": "https://cdnjs.cloudflare.com/ajax/libs/jquery/1.11.3/jquery.js",
    "ember": "https://cdnjs.cloudflare.com/ajax/libs/ember.js/2.1.0/ember.debug.js",
    "ember-data": "https://cdnjs.cloudflare.com/ajax/libs/ember-data.js/2.1.0/ember-data.js",
    "ember-template-compiler": "https://cdnjs.cloudflare.com/ajax/libs/ember.js/2.1.0/ember-template-compiler.js"
  }
}