JavaScript converts string types to dates for comparison

The first applies to: 20100823 This string format
function Datevalid () {
var bd = document.getElementById ("Sstartsavedate"). Value;
var begindate = new Date (Bd.replace (/^ (\d{4}) (\d{2}) (\d{2}) $/, "$1/$2/$3");

var ed = document.getElementById ("Sendsavedate"). Value;
var endDate = new Date (Ed.replace (/^ (\d{4}) (\d{2}) (\d{2}) $/, "$1/$2/$3");

if (begindate >= endDate) {
Alert ("The end time must be greater than the start time!" ");
return false;
}else{
document.getElementById (' Searchform '). Submit ();
}
}
The second applies to: 2010-08-23 This string format
function Datevalid () {
var begindate = new Date (document.getElementById ("Sstartsavedate"). Value.replace (/-/g, "/"));
var endDate = new Date (document.getElementById ("Sendsavedate"). Value.replace (/-/g, "/"));
if (begindate >= endDate) {
Alert ("The end time must be greater than the start time!" ");
return false;
}else{
document.getElementById (' Searchform '). Submit ();
}

The third applies to: 2010/08/23 This string format
function Datevalid () {
var begindate = new Date (document.getElementById ("Sstartsavedate"). Value);
var endDate = new Date (document.getElementById ("Sendsavedate"). Value);
if (begindate >= endDate) {
Alert ("The end time must be greater than the start time!" ");
return false;
}else{
document.getElementById (' Searchform '). Submit ();
}
}

JavaScript converts string types to dates for comparison