使用jQuery停止未完成的Ajax请求

I'm implementing a live search feature on my website(rails). Everytime there is a keypress, I'm submitting the form. But if the user types several characters, several search requests are sent to the server. I was wondering if there is a way to stop the previous(unprocessed) requests. I want only the last request to be successfully processed.I'm implementing a live search feature on my we