var consecutiveDays = 0;
var maxConsecutiveDays = 0;
var lastDate = null;

for (var i = 0; i < dataSetRow["CalendarDate"].length; i++) {
    var currentDate = new Date(dataSetRow["CalendarDate"][i]);
    
    if (lastDate) {
        var diffDays = (currentDate - lastDate) / (1000 * 60 * 60 * 24);
        
        if (diffDays === 1) {
            consecutiveDays++;
        } else {
            if (consecutiveDays > maxConsecutiveDays) {
                maxConsecutiveDays = consecutiveDays;
            }
            consecutiveDays = 1;
        }
    } else {
        consecutiveDays = 1;
    }
    
    lastDate = currentDate;
}

if (consecutiveDays > maxConsecutiveDays) {
    maxConsecutiveDays = consecutiveDays;
}

maxConsecutiveDays;