Adding PHP Code To Page Using JS?

Basically, I have it so that when you click something, then it expands and then shows text. The part I am having trouble at is the text being a php include. Here is the line that works for pre-typed in information:

divbody.innerHTML = "Some random text here.";

Then when I want to do something like this:

divbody.innerHTML = "<?php include('widgets/products.php'); ?>";

Then the actual innerHTML comes out like this:

<!--?php include('widgets/products.php'); ?-->

It seems as if it is changing '<' and '>' to '<!--' and '-->' respectively.