How to calculate the number of days between two dates? [duplicate]

Answer 1

From my little date difference calculator:

var startDate = new Date(2000, 1-1, 1);  // 2000-01-01
var endDate =   new Date();              // Today

// Calculate the difference of two dates in total days
function diffDays(d1, d2)
{
  var ndays;
  var tv1 = d1.valueOf();  // msec since 1970
  var tv2 = d2.valueOf();

  ndays = (tv2 - tv1) / 1000 / 86400;
  ndays = Math.round(ndays - 0.5);
  return ndays;
}

So you would call:

var nDays = diffDays(startDate, endDate);

(Full source at http://david.tribble.com/src/javascript/jstimespan.html.)

Addendum

The code can be improved by changing these lines:

  var tv1 = d1.getTime();  // msec since 1970
  var tv2 = d2.getTime();