remote scripting objects

I don't know if it's IIS or ASP that handles this, but there's a beast called a remote scripting object. It combines JavaScript and ASP to call a remote script on your server without having to submit your browser or load a new page. SO I can add a value to a form field and in the onchange event for that form call a function which resides in a script on the server, it hits a database or whatever and then returns a value that I can display on the same page. Is there any way to do this within a PHP script on Linux?