function checkUsername()
{
	switch(xmlHttp.readyState) {
		case 0 : // Uninitialized
			break;
		case 1 : // Loading
			document.getElementById('divLoading').innerHTML = "Provera korisnickog imena";
			break;
		case 4 : // Complete
			if(xmlHttp.status == 200) {
				var responseType = xmlHttp.getResponseHeader("Content-Type"); 
				if (responseType == "text/html") { 
					var returnedData= xmlHttp.responseText;
					var newline		= returnedData.indexOf('\r\n');
					var parameters	= returnedData.substring(0, newline);
					returnedData	= returnedData.substring(newline+2);
					
					var parameter	= parameters.split('|');
					var valid		= parameter[0];
					var message		= parameter[1];
					var sugestValue	= parameter[2];
					
					if (valid == 0) {
						if (sugestValue != 'Error') {
							returnedData += message + sugestValue;
							document.getElementById('userUsername').value = sugestValue;
						} else
							document.getElementById('userUsername').value	= '';	
					} else if (valid == 1) {
						if (sugestValue != '') {
							document.getElementById('userUsername').value = sugestValue;
						}
					}
					
					document.getElementById('tdUsername').innerHTML = returnedData;
					document.getElementById('divLoading').innerHTML = '';
				} else { 
					document.getElementById('divLoading').innerHTML = '';
					alert("Pogresna povratna vrednost"); 
				} 
			}
			break;
	}
	
	return true;
}