How to remove everything after "?" from string (URL+tracking code)?

[pstein]

Occasionally webpages show an URL with an appended "?" and a tracking code like

http://www.foobar.com/some/path/before.html?after-is-tracking=12345

Assume I assign this URL to a variable:

How can I remove (with Javascript or even better with jQuery)  everything after "?" including the "?" itself?

[dsonesuk]

var url = "http://www.foobar.com/some/path/before.html?after-is-tracking=12345";

var cleanurl="";

cleanurl=url.split("?")[0];