function checkDate(from_date, to_date){
var v_result;
var v_from_date = new Date(parseInt(from_date.substring(0,4),10) - 1900, parseInt(from_date.substring(4,6),10) - 1, parseInt(from_date.substring(6,8),10));
var v_to_date = new Date(parseInt(to_date.substring(0,4),10) - 1900, parseInt(to_date.substring(4,6),10) - 1, parseInt(to_date.substring(6,8),10));
<script>
var date1=new Date("1984/3/7");
var date2=new Date();
var datediff=date2-date1;
alert("date1="+date1.toLocaleString());
alert("date2="+date2.toLocaleString());
if(datediff>0)alert("date2晚于date1")
else alert("date2早于date1");
var datediff=parseInt(datediff/(24*60*60*1000));
alert(datediff+"天");
</script>