If you'd like for certain content to be shown on HTML export, but not on PDF export, you can write a scriptlet like this:
<% if (writer.contextType() == "html") { %>
This rich text will be shown only on HTML export!
<% } %>
You can grab the aliases for a page, and then loop through them like so:
<%
var aliases = page.aliasDisplayNames();
for (i = 0; i < aliases.count(); i++) {
var name = aliases[i];
writer.write(name + "<br/>");
}
%>