Backbone collection filter

HTML

<script src="https://cdnjs.cloudflare.com/ajax/libs/jquery/3.1.1/jquery.js"></script>
<script src="https://cdnjs.cloudflare.com/ajax/libs/underscore.js/1.8.3/underscore.js"></script>
<script src="https://cdnjs.cloudflare.com/ajax/libs/backbone.js/1.3.3/backbone.js"></script>
<button id="mapp">showMappings</button>
<p id="result">

</p>

JavaScript

console.log("start --- ");
$("#mapp").click(function() {
  showMappings();
});

var Connector = Backbone.Model.extend({
  val: 5,
  initialize: function() {
    this.set('val', 3);
  }
});

var Set = Backbone.Collection.extend({
  model: Connector,
  url: "/connectors"
});

var con = new Connector();
var set = new Set([con]);

function showMappings() { //on button click
  console.log("button clicked");
  var fil = set.filter(d => d.get('val') === 3);
  console.log(fil);
}