Property settling

components.my-component.js

import Ember from 'ember';
import { observer } from '@ember/object';

export default Ember.Component.extend({
  obsCallCount: 0,
  
  prop1: null,
  prop2: null,
  
  prop1Observer: observer('prop1', function () {
    this.set('prop2', this.get('prop1'));
  }),
  
  prop2Observer: observer('prop2', function () {
    this.set('prop1', this.get('prop2'));
    this.set('obsCallCount', this.get('obsCallCount') + 1);
  }),
});

controllers.application.js

import Ember from 'ember';

export default Ember.Controller.extend({
  appName: 'Ember Twiddle'
});

templates.application.hbs

<h1>Welcome to {{appName}}</h1>
<br>
<br>
{{outlet}}
{{my-component}}
<br>
<br>

templates.components.my-component.hbs

CallCount: {{obsCallCount}}

{{input value=prop1}}

twiddle.json

{
  "version": "0.15.0",
  "EmberENV": {
    "FEATURES": {}
  },
  "options": {
    "use_pods": false,
    "enable-testing": false
  },
  "dependencies": {
    "jquery": "https://cdnjs.cloudflare.com/ajax/libs/jquery/3.3.1/jquery.js",
    "ember": "3.2.2",
    "ember-template-compiler": "3.2.2",
    "ember-testing": "3.2.2"
  },
  "addons": {
    "ember-data": "3.2.0"
  }
}