function filtresaisi(typefiltre)
{
	keycaractere=(event.keyCode);
	alpha=(keycaractere>=97 && keycaractere<=122 || keycaractere>=65 && keycaractere<=90);
	num=(keycaractere>=48 && keycaractere<=57);
	alphanum=alpha || num;
	switch (typefiltre)
	{
		case "alpha":
			condition=alpha;
			break;
		case "num":
			condition=num;
			break;
		case "alphanum":
			condition=alphanum;
			break;
		default: 
			alert("filtreincorrecte");
			return false;
			break;
	}
	if(condition==false)
	{
		event.keyCode=0;
	}
}