24 小时时间比较大小

function CompareDate(t1,t2)
{
var date = new Date();
var a = t1.split(":");
var b = t2.split(":");
return date.setHours(a[0],a[1]) > date.setHours(b[0],b[1]);
}
调用：
alert( CompareDate("12:00","11:15") );