Bootstrap datetimepicker difference days exclude weekend days (Saturday and Sunday)

Question

Screenshot : img

I want the result is = Diff 1 day, without counting Saturday and Sunday. How to?

Javascript :

$(function() {
    $('#startDateTime, #endDateTime').datetimepicker({   
        format: 'DD/MM/YYYY',
        daysOfWeekDisabled: [0,6]
    });
    $("#startDateTime").on("dp.change", function(e) {
        $('#endDateTime').data("DateTimePicker").minDate(e.date);
    });
    $("#endDateTime").on("dp.change", function(e) {
        $('#startDateTime').data("DateTimePicker").maxDate(e.date);
        CalcDiff()
    });
});

function CalcDiff(){
    var a=$('#startDateTime').data("DateTimePicker").date();
    var b=$('#endDateTime').data("DateTimePicker").date();
    var timeDiff=0
    if (b) {
        timeDiff = (b - a) / 1000;
    }
    $('#diff').text(Math.floor(timeDiff/(60*60*24)))
}