Calculated value is view only.

Hi everyone,

I'm new in sharepoint development, and need some help.

I have sharepoint list for vacation applications. And have javascript code which calculating working days and next working day for employees. Script is working fine, only problem is that sharepoint showing calculation result in column, but when I click save the field is empty. Looks like its view only.

Thanks to everyone who can help

Here is my code.

<script type="text/javascript" language="javascript">

document.addEventListener("DOMContentLoaded", function(event) {
    var from = document.getElementById('Element ID');
    var to = document.getElementById('Element ID');
    var days_count = document.getElementById('Element ID');
    var next_working_day = document.getElementById('Element ID');
    var start_date, end_date, vacation_days = 0;
    function setNextWorkingDay() {
        initEndtDate();
        if(end_date.getDay() == 5) {
            end_date.setDate(end_date.getDate()+3);
            next_working_day.value = end_date.getDate() + '.' + (end_date.getMonth() + 1) + '.' + end_date.getFullYear();
            return false;
        }

        if(end_date.getDay() == 6) {
            end_date.setDate(end_date.getDate()+2);
            next_working_day.value = end_date.getDate() + '.' + (end_date.getMonth() + 1) + '.' + end_date.getFullYear();
            return false;
        }
        end_date.setDate(end_date.getDate()+1);
        console.log('next ',end_date);
        next_working_day.value = end_date.getDate() + '.' + (end_date.getMonth() + 1) + '.' + end_date.getFullYear();
    }

    function dateDiff( date1, date2 ) {
      
      var one_day=1000*60*60*24;

      
      var date1_ms = date1.getTime();
      var date2_ms = date2.getTime();

      var difference_ms = date2_ms - date1_ms;
        
      return Math.round(difference_ms/one_day); 
    }
    function calculate_vacation_days() {
        
        if(typeof start_date === "undefined" || typeof end_date === "undefined") {
            return false;
        }

        if(dateDiff(start_date, end_date) < 0) {
            console.log('wrong dates');
            return false;
        }

        console.log(start_date, end_date);
       
        while (start_date_x = iterable_start_date) {
            

            if (start_date_x.toLocaleDateString() === end_date.toLocaleDateString()) {
                if (start_date_x.getDay() !== 0 && start_date_x.getDay() !== 6) {
                    vacation_days++
                } 
                break;
            }
            if (start_date_x.getDay() !== 0 && start_date_x.getDay() !== 6) {
                vacation_days++
            } 
            iterable_start_date.setDate(iterable_start_date.getDate() + 1);
        }
        days_count.value = vacation_days;
        console.log(vacation_days)
        setNextWorkingDay();
    }

    function initStartDate() {
         var start_date_array = from.value.split('.');
        if(typeof start_date_array[0] === "undefined" || typeof start_date_array[1] === "undefined" || typeof start_date_array[2] === "undefined" ) {
            return false;
        }

        start_date = new Date(start_date_array[2], parseInt(start_date_array[1]) - 1, parseInt(start_date_array[0]));
        iterable_start_date = new Date(start_date_array[2], parseInt(start_date_array[1]) - 1, parseInt(start_date_array[0]));
        iterable_end_date = new Date(start_date_array[2], parseInt(start_date_array[1]) - 1, parseInt(start_date_array[0]));
        temp_start_date = new Date(start_date_array[2], parseInt(start_date_array[1]) - 1, parseInt(start_date_array[0]));
    }

    function initEndtDate(){
        var end_date_array = to.value.split('.');
        if(typeof end_date_array[0] === "undefined" || typeof end_date_array[1] === "undefined" || typeof end_date_array[2] === "undefined" ) {
            return false;
        }
        end_date = new Date(end_date_array[2], parseInt(end_date_array[1] - 1), parseInt(end_date_array[0]));
    }
    from.addEventListener('blur', function(e) {
        e.stopPropagation();
        console.log("from event fired");
        vacation_days = 0
        days_count.value = '';
        initStartDate()
        initEndtDate();
        calculate_vacation_days();
    });
    to.addEventListener('blur', function(e) {
        e.stopPropagation();
        console.log("to event fired");
        vacation_days = 0;
        days_count.value = ''
        initStartDate();
        initEndtDate();

        calculate_vacation_days();
    });
 
    days_count.addEventListener('change', function(e) {
        e.stopPropagation();
        console.log("days_count event fired");
        var days_to_increment = days_count.value;
        initStartDate();
        // start from 1 as first day is already in "iterable_end_date"
        for (var i = 1; i < days_to_increment; i++) {
            console.log(i);
            console.log(iterable_end_date.getDay());
            if (iterable_end_date.getDay() == 6) {
                console.log('sat');
                iterable_end_date.setDate(iterable_end_date.getDate() + 1);
            }

            if (iterable_end_date.getDay() == 0) {
                console.log('sun');
                iterable_end_date.setDate(iterable_end_date.getDate() + 1);
            }
            console.log(iterable_end_date.getDay());
            iterable_end_date.setDate(iterable_end_date.getDate() + 1);
            temp_start_date.setDate(temp_start_date.getDate() + 1);
             if (iterable_end_date.getDay() == 6) {
                console.log('sat');
                iterable_end_date.setDate(iterable_end_date.getDate() + 1);
            }
            if (iterable_end_date.getDay() == 0) {
                console.log('sun');
                iterable_end_date.setDate(iterable_end_date.getDate() + 1);
            }

            console.log(iterable_end_date,temp_start_date);
        }
        
        to.value = iterable_end_date.getDate() + '.' + (iterable_end_date.getMonth() + 1) + '.' + iterable_end_date.getFullYear();

        setNextWorkingDay();
    });
 
});
</script>