New Twiddle

adapters.application.js

import DS from 'ember-data';

export default DS.RESTAdapter;

application.controller.js

import Ember from 'ember';

export default Ember.Controller.extend({
	actions: {
    saveCount(event) {
      let model = this.get('model');
      let value = parseInt(event.target.value);

      model.set('count', value);
      model.save();
    }
  }
});

application.route.js

import Ember from 'ember';

new Pretender(function() {
  this.get('/counters/123', function() {
    return [200, {}, JSON.stringify({
      counter: { id: '123', count: 0 }
    })];
  }, 1000);
  
  this.put('/counters/123', function(request) {
    let count = JSON.parse(request.requestBody).counter.count;

    return [200, {}, JSON.stringify({
      counter: { id: '123', count: count }
    })];
  }, 1000);
});

export default Ember.Route.extend({
  model() {
    return this.store.find('counter', '123');
  }
});

application.template.hbs

<h1>Weird behaviour with Model#save()</h1>
<p>
Click on the number input below to give it focus. Quickly press <code>up</code> three times. This will trigger 3 <code>Model#save()</code> with calls. I've set it up to use Pretender and delay the "server" response by one second.
</p>
<p>
The weird behaviour is that you will see 1-2-3 flash by a second time as each of the <code>Model#save()</code> calls complete.
</p>
<p>
<label>Count:</label>
<input type='number'
			 value={{model.count}}
       oninput={{action 'saveCount'}}>
</p>
  
<br>
<br>

models.counter.js

import DS from 'ember-data';

export default DS.Model.extend({
  count: DS.attr('number')
});

twiddle.json

{
  "version": "0.6.0",
  "EmberENV": {
    "FEATURES": {}
  },
  "options": {
    "enable-testing": false
  },
  "dependencies": {
    "jquery": "https://cdnjs.cloudflare.com/ajax/libs/jquery/1.11.3/jquery.js",
    "ember": "https://cdnjs.cloudflare.com/ajax/libs/ember.js/2.3.1/ember.debug.js",
    "ember-data": "https://cdnjs.cloudflare.com/ajax/libs/ember-data.js/2.3.3/ember-data.js",
    "ember-template-compiler": "https://cdnjs.cloudflare.com/ajax/libs/ember.js/2.3.1/ember-template-compiler.js",
    "route-recognizer": "https://npmcdn.com/[email protected]",
    "fake-xml-http-request": "https://npmcdn.com/[email protected]",
    "pretender": "https://npmcdn.com/[email protected]"
  }
}