How to parse a rendered web page containing javascript

How can one extract data from a rendered web page? In which java script would update the data with time. Is it possible to write user script which can access varibles from webpage java script? Please sugg开发者_运维问答est possible way to achieve this.

according to Turing's Halting Problem Theorem, you can't.

That's what we mean when we say that JavaScript is a Turing complete language. The only way is to execute the JavaScript and let it render the page.

it depends on your programming language.

In C# you could use a webbrowser control, then use the Webbrowser.Document property to get a HTMLDocument object to get the current markup. To invoke javascript function in the document, use the ObjectForScripting property of the Browser control.