glimmer

controllers.application.js

import Ember from 'ember';

export default Ember.Controller.extend({
  
  fields: Ember.A(),
 
  actions: {
 
    // doesn't work
    addField( ) {
			let fields = this.get('fields');
      fields.insertAt(0, {
         label: '1'
       });
      this.set('fields', fields);
		},
    
    // doesn't work when the line 42 is updated to
    // fields.objectAt(1) or fields.objectAt(2)
    // addField( ) {
		//	let fields = this.get('fields');
    //  fields.pushObject({
    //     label: '1'
    //   });
    //  this.set('fields', fields);
		// },
    
    // works when the line 42 is updated to
    // fields.objectAt(1) or fields.objectAt(2)
    // addField( ) {
		//	let fields = this.get('fields');
    //  fields.pushObjects([{
    //     label: '1'
    //   }, {
    // 		 label: '2'
    //	 }]);
    //  this.set('fields', fields);
		// },
   
		addToField( ) {
      let fields = this.get('fields');
      let currentField = fields.objectAt(0);
      let label = currentField.label + '1';
      Ember.set(currentField, 'label', label);
      console.log(fields, currentField);
		} 
	}
});

templates.application.hbs

{{#each fields as |field|}}
	<p>{{field.label}}</p>
{{/each}}
<button {{action 'addField'}}>Add field</button>
<button {{action 'addToField'}}>Append to field </button>
<br>
<br>

twiddle.json

{
  "version": "0.10.4",
  "EmberENV": {
    "FEATURES": {}
  },
  "options": {
    "use_pods": false,
    "enable-testing": false
  },
  "dependencies": {
    "jquery": "https://cdnjs.cloudflare.com/ajax/libs/jquery/1.11.3/jquery.js",
    "ember": "alpha",
    "ember-data": "2.7.0",
    "ember-template-compiler": "alpha"
  },
  "addons": {}
}