function isDateTime(str)
{
var r = str.match(/^(\d{1,4})(-|\/)(\d{1,2})\2(\d{1,2})$/);
if(r==null)return false;
var d= new Date(r[1], r[3]-1, r[4]);
return (d.getFullYear()==r[1] && (d.getMonth()+1)==r[3] && d.getDate()==r[4]);
}
alert(isDateTime("2004-1-5"));
alert(isDateTime("2004-1-45"));