Embeddable widgets
<link rel="import" href="import-file.html">
<element name="x-button" extends="button" constructor="CustomButton">
<template>...</template>
<script>
/// ...
</script>
</element>
DOM change events
Object.observe
Embeddable widgets
<link rel="import" href="import-file.html">
<element name="x-button" extends="button" constructor="CustomButton">
<template>...</template>
<script>
/// ...
</script>
</element>
DOM change events
Object.observe