New Twiddle

components.my-component.js

import Ember from 'ember';

const DURATION = 5000
export default Ember.Component.extend({
  incrementingValue: 0,
  
  foo: Ember.observer('endVal', function(){
    if (this.timer) {
      Ember.run.cancel(this.timer)
    }
    
    this.startAnimation()
  }),
  
  startAnimation() {
    let endVal = this.get('endVal')
    let incrementingValue = this.get('incrementingValue')
                                     
    if (endVal === incrementingValue) {
      return
    }
    
    let range = endVal - incrementingValue
    let increment = endVal > incrementingValue ? 1 : -1;
    let stepTime = Math.abs(Math.floor(DURATION / range));
    
    console.log(stepTime, increment)
    this.scheduleAnimation(stepTime, increment)
	},
  
  scheduleAnimation(stepTime, increment) {
  	let endVal = this.get('endVal')
    let incrementingValue = this.get('incrementingValue')
    
    if (endVal === incrementingValue) {
      return
    }
  
  	let timer = Ember.run.later(this, function() {
      let val = Math.round(incrementingValue + increment)
			this.set('incrementingValue', val)
      this.scheduleAnimation(stepTime, increment)
		}, stepTime)
    
    this.set('timer', timer)
	}
});

controllers.application.js

import Ember from 'ember';

export default Ember.Controller.extend({
  appName: 'Ember Twiddle',
  
  endVal: 137,
  
  actions: {
    fireEvent() {
  		this.set('endVal', Math.round(Math.random()*1000))
    }
  }
});

templates.application.hbs

<h1>Welcome to {{appName}}</h1>
<br>
<br>
{{my-component endVal=endVal}}
<br>
<br>
{{endVal}}
<button onclick={{action "fireEvent"}}>Fire</button>

templates.components.my-component.hbs

{{incrementingValue}}

twiddle.json

{
  "version": "0.15.1",
  "EmberENV": {
    "FEATURES": {}
  },
  "options": {
    "use_pods": false,
    "enable-testing": false
  },
  "dependencies": {
    "jquery": "https://cdnjs.cloudflare.com/ajax/libs/jquery/3.3.1/jquery.js",
    "ember": "3.4.3",
    "ember-template-compiler": "3.4.3",
    "ember-testing": "3.4.3"
  },
  "addons": {
    "ember-data": "3.4.2"
  }
}