I have some HTML files, and each one of them I want to partially render in another HTML file, for example header.html and footer.html in order to o         
        
If you're just using plain HTML and Javascript, you could include jQuery and use an AJAX request to load the contend of another HTML page in your main page.
Have a look at the jQuery 'load()' function here:
http://api.jquery.com/load/
Assuming your have the following html:
your usage would look something like this:
$('#header').load('header.html');
$('#footer').load('footer.html');