JS cross-post substitution slash IE6 date comparison __js

<script type= "Text/javascript" >
var end = "2012-12-12";
var end = End.replace (/-/g, "/");
 Replace All "-", g for global flag, plus if I ignore case: 2012/12/12
alert (end);
var start = "2012-12-11";
Start =start.replace (/-/g, "/");
Alert (Date.parse (end)-date.parse (start));
</script>

Previously written good code on the chrome display normal, but the client machine is IE6, the project manager asked me to modify, IE6 can not parse the string, can only be converted. So it's the following.

var a= date.parse ("2012-12-12")-date.parse ("2012-11-11");

Modified: (not only to achieve a cross slash, but also to achieve a date comparison)