php - Ajax verify page before executing -

I have an ajax.php file on which all of my AJAX call scripts indicate with the additional parameter that the current call Demand is for execution. My problem is that I want to limit some scripts to execute only by specific pages, for example sendComment.php is only www.mysite.com/user/ {any User} . .

Whatever I have done, it is put on top of every script, which I want to limit:

  if (Strstr ($ _ server) HTTP_REFERRER '],' mysite.com/{page_allowed_to_exec_script} ') {then work here}   
 But the information I received is that all Browsers do not support HTTP_REFERRER (I have probably mistakenly written that I am writing it in memory), and there is also pain in the butt when it is not a cross-browser. This stuff can be decoded in all the rabbits files and it is going to be a big pain. It comes to altering the stuff. I see in a way that possibly all the scripts placed in the array with all those pages. Which are capable of executing them, and initially do a check in ajax.php file.  
 Does anyone know how this can be achieved?   
 
 
 If you control the reference page, Or you can use the URL if you think it is important. Uarn, then your only option session the other two can be easily removed.