Who Add “_” Single Underscore Query Parameter?

Question

I have a PHP server running on Apache, I get lots of request looks like this,

10.1.1.211 - - [02/Sep/2010:16:14:31 -0400] \"GET /request?_=1283458471913&         


        

Answer 1

Ajax tools, like jQuery, is able to ask the browser not to cache the requested result, so every request from the loaded web page will travel to web server and get the newest response.

In order to achieve that, set cache flag as false, then an additional query parameter, like _=1234567890, is appended into the request URL. Of course the number is always changing, so the browser thinks it as a brand-new request and won't provide any cached things.