Count number of days between two dates with javascript

Question

I get a date from a datetime picker with this:

var endDate = new Date();
endDate = $("input[id$='DateTimeControl2Date']").val()

Then I find another date and try to check how many days there are between these two dates but I get the error "Object doesn't support this property or method". What am I doing wrong?

$('.StatusDateTable').each(function() {
var statusDate = new Date(); 
statusDate = $(this).find(".dates").html();
var statusLight = $(this).find(".StatusLight").attr("src");
statusLight = statusLight.substring(33).slice(0,-9);
if (statusLight == "Blue") {
var oneDay = 1000*60*60*24;

alert(endDate + statusDate);
var date1_ms = endDate.getTime();
var date2_ms = statusDate.getTime();

var dayDifference = Math.abs(Math.round((date1_ms - date2_ms)/oneDay));

alert(dayDifference);

}
});

endDate has the format of 02/09/2010 and statusDate 1/09/2010.

Thanks in advance.

Answer 1

Date() is a constructor function, when you call it you're assigning the result of that constructor to a variable. Then, in the line afterwards you're assigning a different object, the result of the jQuery val() method, to the same variable.

// The next line will overwrite the current value of `endDate`
endDate = $("input[id$='DateTimeControl2Date']").val()

Date() accepts an argument that will be parsed as the date. This is how you correctly set a new date object to a specific date/time:

var endDate = new Date($("input[id$='DateTimeControl2Date']").val());

This assumes that the date is returned in a format that Date() can parse. The same applies to your statusDate variable.

---

Just seen the format of the two dates at the bottom, which won't work well when being parsed by Date() . They won't parse at all in IE, and other browsers parse them as if they were mm/dd/yyyy format. This means you will have to manually split them and apply them to the Date() constructor:

 var endDateSplit = $("input[id$='DateTimeControl2Date']").val().split("/"), endDate = new Date(endDateSplit[2], endDateSplit[1]-1, endDateSplit[0]); 

Answer 2

For date manipulation in javascript, there is this library :

http://www.datejs.com/