my-element.html

<!-- Imports polymer -->
<link rel="import" href="../polymer/polymer.html">

<!-- Defines element markup -->
<dom-module id="my-element">
    <template></template>
    
    <!-- Registers custom element -->
    <script>
    Polymer({
        is: 'my-element',
    
        // Fires when an instance of the element is created
        created: function() {},
    
        // Fires when the local DOM has been fully prepared
        ready: function() {},
    
        // Fires when the element was inserted into the document
        attached: function() {},
    
        // Fires when the element was removed from the document
        detached: function() {},
    
        // Fires when an attribute was added, removed, or updated
        attributeChanged: function(name, type) {}
    });
    </script>
</dom-module>