JSFiddle - React, Tailwind, and code Playground

HTML

<script src="//cdnjs.cloudflare.com/ajax/libs/underscore.js/1.7.0/underscore-min.js"></script>
<script src="http://squizzle.me/js/sqimitive/sqimitive.min.js"></script>

JavaScript

var MyItem = Sqimitive.Sqimitive.extend()

var MyList = Sqimitive.Sqimitive.extend({
  _owning: false,
  _childClass: MyList,
  _childEvents: ['change'],
})

var item = new MyList

var list1 = new MyList
list1.nest(item)

var list2 = new MyList
list2.nest(item)

alert(list1.length + ' ' + list2.length)
  // alert('1 1')