executing javascript functions with WebRequest/WebResponse object and obtaining page html

I have retrieved the html of a web page using the WebRequest object but the page itself does not contain the information I need to extract.  There is a javascript function which runs once the page is loaded which then retrieves and adds the information I need to the page.  Is there a way of performiing some sort of GET/POST operation which will execute the required javascript function and return the html of the completed page (which contains the information I need)?