Id:

Item Detail:

var xhr = createRequest(); function getData(dataSource, divID, id,itemd) { if(xhr) { var obj = document.getElementById(divID); var requestbody ="idd="+encodeURIComponent(id)+"&itd="+encodeURIComponent(itemd); xhr.open("POST", dataSource, true); xhr.setRequestHeader("Content-Type", "application/x-www-form-urlencoded"); xhr.onreadystatechange = function() { if (xhr.readyState == 4 && xhr.status == 200) { obj.innerHTML = xhr.responseText; } // end if } // end anonymous call-back function xhr.send(requestbody); } // end if } // end function getData()

$id= $_POST["idd"]; $item_detail= $_POST["itd"];

            $xml = new DomDocument();
            $xml->load("item.xml");
            $xml->formatOutput = true;   
            $items = $xml->firstChild;     
            $item = $xml->createElement('item');   
            $items->appendChild($item); 
            $id = $xml->createElement('id');
            $itemdetail = $xml->createElement('itemdetail'); 
            $item->appendChild( $id );
            $id->nodeValue = $id;
            $item->appendChild( $itemdetail );
            $ItemDetail->nodeValue = $item_detail;
            
              
            $xml->save("item.xml");
           
           }

 <form>
     <p>Id:<input type="text" name= "id" size="10" /> </p>
     <p>Item Detail:<textarea name="item_detail" rows="3" cols="50" ></textarea></p>
     <input name="submit" type = "button" onClick = "getData('data.php','info', id.value, ,item_detail.value)" value = "Add Item" />
    
</form>    
    
 <div id="info"> </div>

var xhr = createRequest();
function getData(dataSource, divID, id,itemd) {
if(xhr) {
var obj = document.getElementById(divID);
var requestbody ="idd="+encodeURIComponent(id)+"&itd="+encodeURIComponent(itemd);
xhr.open("POST", dataSource, true);
xhr.setRequestHeader("Content-Type", "application/x-www-form-urlencoded");
xhr.onreadystatechange = function() {
if (xhr.readyState == 4 && xhr.status == 200) {
obj.innerHTML = xhr.responseText;
} // end if
} // end anonymous call-back function
xhr.send(requestbody);
} // end if
} // end function getData()

$id= $_POST["idd"];
$item_detail= $_POST["itd"];


            $xml = new DomDocument();
            $xml->load("item.xml");
            $xml->formatOutput = true;   
            $items = $xml->firstChild;     
            $item = $xml->createElement('item');   
            $items->appendChild($item); 
            $id = $xml->createElement('id');
            $itemdetail = $xml->createElement('itemdetail'); 
            $item->appendChild( $id );
            $id->nodeValue = $id;
            $item->appendChild( $itemdetail );
            $ItemDetail->nodeValue = $item_detail;
            
              
            $xml->save("item.xml");
           
           }