ajax+asp+php User name detection and database

ajax+asp Tutorial +php Tutorial user name detection and database tutorial
function GetResult (str)
{
$ ("Regusernameinfo"). Innerhtml= ' <font color=red> detection, please wait ...</font> ';
var xmlhttp = createxmlhttprequest ();
Xmlhttp.open ("Get", "member/regcheck.asp?rtype=1&/=" +escape (str), true);
Xmlhttp.onreadystatechange=function ()
{
if (xmlhttp.readystate==4)
{

if (xmlhttp.status==200)
{
if (xmlhttp.responsetext==0)
{
$ ("Regusernameinfo"). Innerhtml= ' verified through, can register normally ';
}
else if (xmlhttp.responsetext==1)
{
$ ("Regusernameinfo"). Classname= "show null";
$ ("Regusernameinfo"). Innerhtml= ' Sorry, username [<b> ' + str + ' </b>] has been registered, please complete the registration with a different user name. '
}
Else
{
$ ("Regusernameinfo"). Classname= "show null";
$ ("Regusernameinfo"). Innerhtml= ' Format error, please confirm input ';
}
}
}
}
Xmlhttp.send (NULL);
}