function checkCoupon(str){

   if (window.XMLHttpRequest) {
            // code for IE7+, Firefox, Chrome, Opera, Safari
            xmlhttp=new XMLHttpRequest();
        } else { // code for IE6, IE5
            xmlhttp=new ActiveXObject("Microsoft.XMLHTTP");
        }
        xmlhttp.onreadystatechange=function() {
            if (this.readyState==4 && this.status==200) {
               alert('success');
            }
        }

        xmlhttp.open("GET","https://www.example.com/inc/checkCoupon?id=45&coupon="+str,true);

        xmlhttp.send();
    }

#Rewrite everything to https
RewriteEngine On
RewriteCond %{HTTPS} !=on
RewriteRule ^(.*)$ https://%{HTTP_HOST}%{REQUEST_URI} [L,R=301]

RewriteCond %{HTTP_HOST} !^www. [NC]
RewriteRule ^(.*)$ http://www.example.com/$1 [L,R=301]

RewriteCond %{HTTPS} !=on
RewriteRule ^(.*)$ https://%{HTTP_HOST}%{REQUEST_URI} [L,R=301]

RewriteBase /
RewriteCond %{REQUEST_FILENAME} !-f
RewriteCond %{REQUEST_URI} !(.*)/$
RewriteRule ^(.*)$ http://www.example.com/$1/ [L,R=301]