<html>
  <head>
    <meta http-equiv="content-type" content="text/html; charset=utf-8">
    <meta name="viewport"
      content="width=device-width, initial-scale=1.0, maximum-scale=1, user-scalable=0" />
    <title>Vanilla JavaScript Feathers Chat</title>
    <link rel="shortcut icon" href="favicon.ico">
    <link rel="stylesheet" href="//cdn.rawgit.com/feathersjs/feathers-chat/v0.2.0/public/base.css">
    <link rel="stylesheet" href="//cdn.rawgit.com/feathersjs/feathers-chat/v0.2.0/public/chat.css">
  </head>
  <body>
    <div id="app" class="flex flex-column"></div>
    <script src="//cdnjs.cloudflare.com/ajax/libs/moment.js/2.12.0/moment.js"></script>
    <script type="text/javascript" src="//cdnjs.cloudflare.com/ajax/libs/core-js/2.1.4/core.min.js"></script>
    <script src="//npmcdn.com/feathers-client@^2.0.0-pre.1/dist/feathers.js">
    </script>
    <script src="/socket.io/socket.io.js"></script>
    <script src="app.js"></script>
  </body>
</html>

<html>
  <head>
    <meta http-equiv="content-type" content="text/html; charset=utf-8">
    <meta name="viewport"
      content="width=device-width, initial-scale=1.0, maximum-scale=1, user-scalable=0" />
    <title>Vanilla JavaScript Feathers Chat</title>
    <link rel="shortcut icon" href="favicon.ico">
    <link rel="stylesheet" href="//cdn.rawgit.com/feathersjs/feathers-chat/v0.2.0/public/base.css">
    <link rel="stylesheet" href="//cdn.rawgit.com/feathersjs/feathers-chat/v0.2.0/public/chat.css">
  </head>
  <body>
    <div id="app" class="flex flex-column"></div>
    <script src="//cdnjs.cloudflare.com/ajax/libs/moment.js/2.12.0/moment.js"></script>
    <script src="//npmcdn.com/feathers-client@^2.0.0-pre.1/dist/feathers.js">
    </script>
    <script src="/socket.io/socket.io.js"></script>
    <script src="app.js"></script>
  </body>
</html>

Remove core.js from Vanilla JavaScript example
Remove core.js from Vanilla JavaScript example
