在JavaScript中，如何判断一个日期是否大于今天的日期？

var GivenDate = '2015-02-22';
var CurrentDate = new Date();
GivenDate = new Date(GivenDate);
if(GivenDate > CurrentDate){
    alert('Given date is greater than the current date.');
}else{
    alert('Given date is not greater than the current date.');
}