Ajax has no code to refresh the application when registering the user name


var xmlHttp; 
Unname() / / when the user name loses focus

All L1.innerhtml= “cannot be empty!”; The
  xmlHttp=new ActiveXObject(“Microsoft.XMLHTTP”); 
Xmlhttp Onreadystatechange=deal; / / callback function
Var url= “ajax.aspx? User='” +all Uname+ “‘”; / / you will jump to the page where the user name is detected
Xmlhttp Open (“get”, URL, true); / / submit the form to the URL in the get mode; And start next step processing
Xmlhttp Send (null); / / send


 {return; } 

If (xmlhttp.status! =200) / / an SQL statement or database error occurs when it is equal to 500

Var num = xmlhttp ResponseText; / / receive the information sent by the server
All L1.innertext= “secondary user name has been used!”; The