JavaScript alternative to SSI

Is Javascript capable of doing an "include" in the same way that SSI does?  
For example, rather than doing <!--#include virtual="file" -->  is there a 
way of making the client do the include such as with JavaScript?

I understand the difference between server-side and client-side.  My intent 
is to make a client-side JS call for additional code that would be processed 
by the browser.  Thinking about it when I say it like that, this seems 
unlikely.  The problem is that I thought I saw a thread that said it was 
indeed possible.  "document.write" seems to ring a bell... but I don't know 
enough about javascript to know what I'm talking about.

Help me get started on my research or clarify what I'm getting mixed up in my 
understanding of what I thought I thaw... er, saw.  :)

++Dan

HWG: hwg-languages mailing list archives, maintained by Webmasters @ IWA