nd_item_editor.html

<div>
  <section>
    <div>
      a:
      <span ng-model="ctrl.item.a" contenteditable></span>
    </div>
    <div>
      b:
      <span ng-model="ctrl.item.b" contenteditable></span>
    </div>
    <button ng-click="ctrl.add()">Add</button>
  </section>
  <p>{{ctrl.item.a}},{{ctrl.item.b}}</p>
</div>