Ajax POST request fetch data returned in the background

function Ajax(){varName =Document. getElementById (' username ').value  Encodes special symbols (such as & =) that are passed on//and encoded in Chinese as well. Name = encodeURIComponent (name)varinfo ="Name="+ Name; 1. Create an Ajax objectvarXHR =NewXMLHttpRequest (); 4. Sets the request callback method XHR.onreadystatechange=functionBack () {alert (info);if(XHR.readyState= = 4) {alert (XHR).ResponseText); }//2. Send Request Xhr.open (' Post ','./ajax.php '); 3. Send/Post way data is passed in analog form form the post format of the form is passed to the server through XML (setRequestHeader) the following must be called after the Open method Xhr.setr Equestheader ("Content-type","application/x-www-form-urlencoded") Xhr.send (info); }