Ajax does not need to update the application code when registering a user name

Source: Internet
Author: User

VaR XMLHTTP;
Uname () // when the user name loses focus
{
If (all. uname. = "")
{
All. l1.innerhtml = "cannot be blank! ";
SetTimeout ("close (1)", 1500 );
Return;
}
Else
{
XMLHTTP = new activexobject ("Microsoft. XMLHTTP ");
XMLHTTP. onreadystatechange = deal; // callback function
VaR url = "Ajax. aspx? User = '"+ ALL. uname. +"' "; // the user name to be checked.
XMLHTTP. Open ("get", URL, true); // submit the form to the URL in get mode, and start one step of processing.
XMLHTTP. Send (null); // send
}
}
Deal ()
{
// Alert (XMLHTTP. readystate + "_" + XMLHTTP. status );
If (XMLHTTP. readystate! = 4)
{Return ;}

If (XMLHTTP. status! = 200) // if it is equal to 500, it is an SQL statement or database error.
{Return ;}
//

VaR num = XMLHTTP. responsetext; // receives the message sent by the server.
// Alert (Num );
All. l1.innertext = "";
If (Num> 0)
{
All. l1.innertext = "this user name has been used! ";
}
Else
{
All. l1.innertext = "√ ";
}

}

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