Import an HTML file that will add a div with "Hello, World!" at the end of the main document's DOM tree.
Imported file hello.html:
<script>
var div = document.createElement( 'div' )
div.innerHTML = 'Hello, World!'
document.body.appendChild( div )
</script>
Main file index.html:
<html>
<link rel="import" href="hello.html">