subexpressions

controllers.application.js

import Ember from 'ember';

export default Ember.Controller.extend({
  appName:'Ember Twiddle',
  me: 'me',
  
  actions: {
  	toggle() {
    	this.toggleProperty('currentUser');
    }
  }
});

router.js

import Ember from 'ember';
var Router = Ember.Router.extend({
  location: 'none'
});

Router.map(function() {
});

export default Router;

styles.app.css

body { margin: 12px 16px }

templates.application.hbs

<h1>Welcome to {{appName}}</h1><br><br>{{outlet}}<br><br>
<a onclick={{action 'toggle'}}>Toggle</a>
{{component (concat (if currentUser 'current-' 'test-') me)}}

templates.components.current-me.hbs

<b class="foo">current-me</b>

templates.components.test-me.hbs

<b class="foo">test me</b>