// JavaScript Document
function toggle_username(userid) { 
    if (window.XMLHttpRequest) { 
        http = new XMLHttpRequest(); 
    } else if (window.ActiveXObject) { 
        http = new ActiveXObject("Microsoft.XMLHTTP"); 
    } 
    handle = document.getElementById(userid); 
    var url = '/username.php?'; 
    if(handle.value.length > 0) { 
        var fullurl = url + 'do=check_username_exists&username=' + encodeURIComponent(handle.value);
        http.open("GET", fullurl, true); 
        http.send(null); 
        http.onreadystatechange = statechange_username; 
    }else{ 
        document.getElementById('username_exists').innerHTML = ''; 
    } 
} 

function statechange_username() { 
    if (http.readyState == 4) { 
        var xmlObj = http.responseXML; 
        var html = xmlObj.getElementsByTagName('result').item(0).firstChild.data; 
        document.getElementById('username_exists').innerHTML = html; 
    } 
}