function check_username_send() {

	if (http_request.readyState == 4) {
	
		if (http_request.status == 200) {
	        document.getElementById('check_div').innerHTML = unescape(http_request.responseText);
	    } else {
	        alert('Bei dem Request ist ein Problem aufgetreten.');
	    }
	    
	}

}


function username_send() {
		
	http_request = createRequest();
	http_request.onreadystatechange = check_username_send;
	http_request.open('POST', '../ajax.php', true);
	http_request.setRequestHeader('Content-Type', 'application/x-www-form-urlencoded');
	http_request.send('do=username_check&username=' + document.anmeldung.username.value);

}


function username_del() {
var inhalt_formular = document.getElementById('check_div');

	if(inhalt_formular != '') {
	inhalt_formular.innerHTML = " ";
	}

}