Thanks for the reply.
I've got half of what you are saying already. I have a parameter so that if someone visits the url
http://www.domain.com/search/?crit=searchCriteria, then the search will be performed.
What I want is, if they visit the url
http://www.domain.com/search/, enter their criteria and click on the button, the url will change to
http://www.domain.com/search/?crit=searchCriteria but the page will not reload. The search will be performed using ajax.
Anything I've tried with javascript (like assigning to document.location.search) makes the page reload, which is what I don't want to happen.