updateattrs?

components.x-test.js

import Ember from 'ember';

export default Ember.Component.extend({
  updates: Ember.A(),

  didReceiveAttrs () {
    this._super(...arguments);
    this.get('updates').pushObject('didReceiveAttrs ' + new Date());
  },
  
  didUpdateAttrs () {
    this._super(...arguments);
    this.get('updates').pushObject('didReceiveAttrs ' + new Date());
  }
});

controllers.application.js

import Ember from 'ember';

export default Ember.Controller.extend({
  appName: 'Ember Twiddle',
  arr: Ember.A([ 1, 2, 3 ]),
  
  actions: {
    triggerArrUpdate () {
      this.get('arr').addObject(this.get('arr.lastObject') + 1);
    }
  }
});

templates.application.hbs

Array: {{#each arr as |a|}}{{a}}{{/each}}<br />
<button type="button" {{action "triggerArrUpdate"}}>Trigger Attr Update</button>
{{x-test arr=arr}}

templates.components.x-test.hbs

<ul>
  {{#each updates as |u|}}
    {{u}}
  {{/each}}
</ul>
Array: {{#each arr as |a|}}{{a}}{{/each}}

twiddle.json

{
  "version": "0.10.6",
  "EmberENV": {
    "FEATURES": {}
  },
  "options": {
    "use_pods": false,
    "enable-testing": false
  },
  "dependencies": {
    "jquery": "https://cdnjs.cloudflare.com/ajax/libs/jquery/1.11.3/jquery.js",
    "ember": "2.9.0",
    "ember-data": "2.9.0",
    "ember-template-compiler": "2.9.0",
    "ember-testing": "2.9.0"
  },
  "addons": {}
}