Prototype Object Property

controllers.first-controller.js

import Ember from 'ember';
import mixin from '../mixins/controller-mixin';

export default Ember.Controller.extend(mixin, {
  text: 'First Controller',
  onClick() {
    this.set('mixinProp.value', 'aaa');
  }
});

controllers.other-controller.js

import Ember from 'ember';
import mixin from '../mixins/controller-mixin';

export default Ember.Controller.extend(mixin, {
  text: 'Other Controller',
  onClick() {
    this.set('mixinProp.value', 'bbb');
  }
});

mixins.controller-mixin.js

import Ember from 'ember';

export default Ember.Mixin.create({
  mixinProp: {
    value: '---'
  }
});

router.js

import EmberRouter from '@ember/routing/router';
import config from './config/environment';

const Router = EmberRouter.extend({
  location: 'none',
  rootURL: config.rootURL
});

Router.map(function() {
  this.route('other-controller');
  this.route('first-controller');
});

export default Router;

templates.application.hbs

<div>
  {{#link-to 'first-controller'}}First Controller{{/link-to}} |
  {{#link-to 'other-controller'}}Other Controller{{/link-to}}
</div>

{{outlet}}

templates.other-controller.hbs

<h1>{{text}}</h1>
{{mixinProp.value}}
<button onclick={{action onClick}}>Change text</button>

twiddle.json

{
  "version": "0.14.1",
  "EmberENV": {
    "FEATURES": {}
  },
  "options": {
    "use_pods": false,
    "enable-testing": false
  },
  "dependencies": {
    "jquery": "https://cdnjs.cloudflare.com/ajax/libs/jquery/3.3.1/jquery.js",
    "ember": "2.18.2",
    "ember-template-compiler": "2.18.2",
    "ember-testing": "2.18.2"
  },
  "addons": {
    "ember-data": "2.18.2"
  }
}