<script>
function CheckDateTime(str){
var reg = /^(\d{1,2}):(\d{1,2}):(\d{1,2})$/;
var r = str.match(reg);
if(r==null)return false;
var d= new Date(03,05,24,r[1],r[2],r[3]);
if(d.getHours()!=r[1])return false;
if(d.getMinutes()!=r[2])return false;
if(d.getSeconds()!=r[3])return false;
return true;
}
</script>
<input onblur="alert(CheckDateTime(value))" value="12:20:20">
function CheckDateTime(str){
var reg = /^(\d{1,2}):(\d{1,2}):(\d{1,2})$/;
var r = str.match(reg);
if(r==null)return false;
var d= new Date(03,05,24,r[1],r[2],r[3]);
if(d.getHours()!=r[1])return false;
if(d.getMinutes()!=r[2])return false;
if(d.getSeconds()!=r[3])return false;
return true;
}
</script>
<input onblur="alert(CheckDateTime(value))" value="12:20:20">