[SOLVED] Polymer 2.x code works in jsbin but not in codepen, plunker or jsfiddle

Polymer 2.x code works in jsbin but not in codepen, plunker or jsfiddle

The below code works properly in this jsbin but it does not work in either this codepen, this plunker or this jsfiddle.

Why not? How can I get it to work in the three locations where it does not?

http://jsbin.com/yudavucola/1/edit?html,console,output

<!DOCTYPE html>
<html>
<head>
  <meta charset="utf-8">
  <meta name="viewport" content="width=device-width">
  <title>JS Bin</title>

  <base href="http://polygit.org/polymer+:master/components/">
  <script src="webcomponentsjs/webcomponents-lite.js"></script>
  <link rel="import" href="polymer/polymer-element.html">
  <link rel="import" href="paper-dialog/paper-dialog.html">

  <!-- Ensure Web Animations polyfill is loaded since neon-animation 2.0 doesn't import it -->
  <link rel="import" href="neon-animation/web-animations.html">
  <link rel="import" href="neon-animation/animations/scale-up-animation.html">
  <link rel="import" href="neon-animation/animations/fade-out-animation.html">

</head>
<body>
  <dom-module id="my-el">
    <template>
      <button on-click="open">Open Dialog</button>
      <paper-dialog
        id="dialog"
        entry-animation="scale-up-animation"
        exit-animation="fade-out-animation"
        modal
       >
        <h2>Header</h2>
        <div>Dialog body</div>
      </paper-dialog>
    </template>
    <script>
      class MyEl extends Polymer.Element {
        static get is() { return 'my-el' }

    constructor() {
      super();
        }

        open() {
          console.log('opening...');
          this.$.dialog.open();
          console.log('opened!');
        }

      }

      customElements.define(MyEl.is, MyEl);
    </script>
  </dom-module>

  <my-el></my-el>
</body>
</html>

Solution

Since every other site other than jsbin is using the secure version of HTTP i.e. HTTPS, the request to get the contents from the source http://polygit.org/polymer+:master/components/ is blocked. So, use secure connection and it will work in every other site.

You can check the console for more information.