How to subtract date/time in JavaScript?

This will give you the difference between two dates, in milliseconds

var diff = Math.abs(date1 - date2);

In your example, it'd be

var diff = Math.abs(new Date() - compareDate);

You need to make sure that compareDate is a valid Date object.

Something like this will probably work for you

var diff = Math.abs(new Date() - new Date(dateStr.replace(/-/g,'/')));

i.e. turning "2011-02-07 15:13:06" into new Date('2011/02/07 15:13:06'), which is a format the Date constructor can comprehend.

You can just substract two date objects.

var d1 = new Date(); //"now"
var d2 = new Date("2011/02/01");  // some date
var diff = Math.abs(d1-d2);  // difference in milliseconds