Two Date Differences in JQUERY

var startDate = $('#dateTextField').val();       //i.e 22/9/2011   

var d1 = ddmmyyyyToDate(startDate);        

var endDate = $('#dateTextFieldEndDate').val();         

var d2 = ddmmyyyyToDate(endDate);          //i.e 12/09/2011 

var diff = d2 - d1;                                          //i.e -864000000

alert(startDate +" "+endDate+" "+diff);         

Output: -ve value: End Date is less than Start Date.

              +ve : Success (  Greater than ZERO.)

/*------------------This Function converts Date object into String------------------*/

function ddmmyyyyToDate(str) {

    var parts = str.split("/");                  // Gives us ["dd", "mm", "yyyy"]

    return new Date(parseInt(parts[2], 10),      // Year

                    parseInt(parts[1], 10) - 1,  // Month (starts with 0)

                    parseInt(parts[0], 10));     // Day of month

}