function checkUsername(elem)
{
	var rand = Math.random() * 1.0e+100;

	document.getElementById('usernamecheck').innerHTML = '';
	HTML_AJAX.replace('usernamecheck', 'ajaxHandler.php?node=usernamecheck&text=' + elem.value + '&r=' + rand);
	document.getElementById('usernamecheck').style.visibility = 'visible';
}