get number of sundays in a month using javascript [duplicate]

Answer 1

https://developer.mozilla.org/en-US/docs/JavaScript/Reference/Global_Objects/Date

function sundays(year, month) {

    var day, counter, date;

    day = 1;
    counter = 0;
    date = new Date(year, month, day);
    while (date.getMonth() === month) {
        if (date.getDay() === 0) { // Sun=0, Mon=1, Tue=2, etc.
            counter += 1;
        }
        day += 1;
        date = new Date(year, month, day);
    }
    return counter;
}

console.log(sundays(2012, 5));

Answer 2

function sundaysInMonth( m, y ) {
  var days = new Date( y,m,0 ).getDate();
  var sundays = [ (8 - (new Date( m +'/01/'+ y ).getDay())) % 7 ];
  for ( var i = sundays[0] + 7; i < days; i += 7 ) {
    sundays.push( i );
  }
  return sundays;
}

alert( sundaysInMonth( 10,2012 ) ); //=> [ 7,14,21,28 ]
alert( sundaysInMonth( 10,2012 ).length ); //=> 4