Adding a parameter to the URL with JavaScript

Question

In a web application that makes use of AJAX calls, I need to submit a request but add a parameter to the end of the URL, for example:

Original URL:

Answer 1

Sometime we see ? at the end URL, i found some solutions which generate results as file.php?&foo=bar. i came up with my own solution work perfectly as i want!

location.origin + location.pathname + location.search + (location.search=='' ? '?' : '&') + 'lang=ar'

Note: location.origin doesn't work in IE, here is its fix.