javascript: Sorting Date in an Array (Collection)

function getDateLatest()
{
  var date0 = new Date('12/31/2005');
  var date1 = new Date('11/29/2007');
  var date2 = new Date('01/13/1999');
  
  var dateArray = new Array();

  //we store date as time in milliseconds.
  //getTime() returns the number of milliseconds since
  //midnight of January 1, 1970. This method is also very
  //useful for generating a unique sequence of numbers.
  dateArray[0] = date0.getTime();
  dateArray[1] = date1.getTime();
  dateArray[2] = date2.getTime();
  dateArray.sort(sortNumber);

  var dateLatest = new Date(dateArray[dateArray.length - 1]);
  alert(dateLatest);}        

  //By default, Array sorts alphabetically.  To get it to sort
  //numerically, we write a function that compares numbers.
  function sortNumber(a, b)
  {
     return a - b
  }