moment-weekofmonth.js

gistfile1.js

moment.fn.weekOfMonthFormat = function(format) {
    var formats = format.split("-");
    return moment(formats[0] + "-" + formats[1], "YYYY-MM").weekOfMonth(formats[2]);
}
moment.fn.koDay = function() {
    var day = this.clone().day() || 7;
    return --day;
}
moment.fn.weekOfMonth = function(input) {
    var day = this.clone().date(1).koDay();

    if (input != null) {
        var endOfWeek = input*7 - day;
        var endOfMonth = this.clone().endOf('month').date();
        endOfWeek = Math.min(endOfWeek, endOfMonth);

        return endOfWeek > 0 ? this.date(endOfWeek) : this.add(-1, 'month').endOf('month');
    } else {
        return Math.ceil((this.date() + day) / 7);
    }
}