<div align="center" id="embed-com.example.game.GwtDefinition"></div>
<script type= "text/javascript" src = "com.example.game.GwtDefinition/com.example.game.GwtDefinition.nocache.js"></script>

$('#thebutton').on('click', function(event) {
    $('#thedivtoloadinto').load('separate_html_file.html');
  });

$.getScript('com.example.game.GwtDefinition/com.example.game.GwtDefinition.nocache.js');