Last Day of the Month: Javascript

Calculating the last day of the current month or subsequent months is a common populated form field for quotesrot contracts where an expiry date is required.  Goes a little something like this:

Today's date in MM/DD/YYYY:

// today's date
var d = new Date();
var month = d.getMonth() + 1;
var day = d.getDate();
var year = d.getFullYear();
var vdate = month + "/" + day + "/" + year;

Last day of the next month:

// last day of next month
if (d.getMonth() + 1 == 12) {
  var nmonth = 1;
  var nyear = d.getFullYear() + 1;
  var lastday = new Date(nyear, 1, 0).getDate();
} 
else {
  var nmonth = d.getMonth() + 2;
  var nyear = d.getFullYear();
  var lastday = new Date(nyear, d.getMonth() + 2, 0).getDate();
}
var expdate = nmonth + "/" + lastday + "/" + nyear;

There are a dozen ways to get to this result and always interested in other ways to get the same info.