function getKeyCode(e) {
	if (window.event) {
		return window.event.keyCode;
	}
	else if (e) {
		return e.which;
	}
	else {
		return null;
	}
}

function keyRestrict(e, validchars) { // v3.0
	var key=", keychar=";
	key = getKeyCode(e);
	
	if (key == null) {
		return true;
	}
	
	keychar = String.fromCharCode(key);
	keychar = keychar.toLowerCase();
	validchars = validchars.toLowerCase();
	
	if (validchars.indexOf(keychar) != -1) {
		return true;
	}
	
	if ( key==null || key==0 || key==8 || key==9 || key==13 || key==27 ){
		return true;
	}
	
	return false;
}

/**
Usando:
onKeyPress="return keyRestrict(event,'1234567890.')"
*/