gistfile1.js

function fillHeaderDates(baseDate) {
    var today = (baseDate) ? baseDate : new Date(),
        dayName = getDayForDate(today);

    $('.' + dayName + 'Date').html(getDate(today));

    var daysRight = [],
        daysLeft = [],
        after = false,
        days = ['sunday', 'monday', 'tuesday', 'wednesday', 'thursday', 'friday', 'saturday'];

    days.forEach(function(day) {
        if (after) {
            daysRight.push(day);
        } else if (day === dayName) {
            before = false;
        } else {
            daysLeft.push(day);
        }
    });

    daysLeft.reverse();

    var todayLeft = today;
    daysLeft.forEach(function(day) {
        todayLeft.setDate(todayLeft.getDate() -1);
        $('.' + day + 'Date').html(getDate(todayLeft));
    });

    var todayRight = today;
    daysRight.forEach(function(day) {
        todayRight.setDate(todayRight.getDate() +1);
        $('.' + day + 'Date').html(getDate(todayRight));
    });

}