JSFiddle - React, Tailwind, and code Playground

HTML

<script src="https://github.com/downloads/emberjs/ember.js/ember-0.9.7.1.min.js"></script>

JavaScript

obj = Ember.Object.create({});

a1 = Ember.ArrayController.create({content: []});
a2 = Ember.ArrayController.create({content: []});

a1.pushObject(obj);
a1.pushObject(obj);
a2.pushObject(obj);

obj.destroy()
    
alert(a1.get('content').length)