<script>
function IsDate(str){
var re=/^(\d{4})-(\d{1,2})-(\d{1,2})$/
if(!re.test(str))return false;
var r=str.match(re)
var d=new Date(r[1],r[2]-1,r[3])
return d.getFullYear()==r[1]&&d.getMonth()==r[2]-1&&d.getDate()==r[3]
}
alert(IsDate("2000-2-30"))
</script>