big function

$.get('zadanie.json', function(array) {
    console.log(array);
    array=array.sort(function(a,b){ return a['start_time'] > b['start_time'] ? 1 : -1; });
    var to_output=document.getElementById('main_output');
    var one_day=61;
    function days_til_end(i){
        var temp=array[i]['start_time'];
        var start=temp.charAt(temp.length-2)+temp.charAt(temp.length-1);
        temp=array[i]['end_time'];
        var end=temp.charAt(temp.length-2)+temp.charAt(temp.length-1);
        start=parseInt(start);
        end=parseInt(end);
        var time= end-start;
        var days=(one_day*time)-2;
        if(days<=0){
            return 59;
        }
        else{
            return days;
        }
    }
    function display_top_task(){
        var i=0;
        var top_output=document.getElementById('top_tasks_output')
        var max=array.length;
        do{
            if(array[i]['parent_id']==null || array[i]['parent_id']==""){
                top_output.innerHTML+='<div id='+array[i]['id']+'><div class="top_task"><h2>'+array[i]['name']+'</h2><p>'+array[i]['assignee']+'</p></div></div>';
                var days_to_end=days_til_end(i);
                document.getElementById(array[i]['id']).style.width = days_to_end+'px';
            }
            i++;
        }while(i<max);
    }
    function display_lower_tasks(){
        var i=0;
        var max=array.length;
        do{
            if(array[i]['parent_id']==null || array[i]['parent_id']==""){
            }
            else{
                var id=array[i]['parent_id'];
                if(document.getElementById(id)==null){

                }
                else{
                    var days_to_end=days_til_end(i);
                    document.getElementById(id).innerHTML+='<div id='+array[i]['id']+' class="kid_task" ><div>'+array[i]['name']+'<br><p>'+array[i]['assignee']+'</p></div></div>';
                    document.getElementById(array[i]['id']).style.width = days_to_end+'px';
                    var temp=document.getElementById(array[i]['id'])
                    if(array[i]['status']=="pending"){
                        temp.classList.add("pending");
                    }
                    else if(array[i]['status']=="new"){
                        temp.classList.add("new");
                    }
                    else{
                        temp.classList.add("completed");
                    }
                }
            }
            i++;
        }while(i<max);
    }

    function display_date(){
        var i=0;
        var j=1;
        do{
            document.getElementById('date').innerHTML+='<td>2019-05-'+j+'</td>';
            i++;
            j++;
        }while(i<31);
    }
    function move_day(){
        document.getElementById('34').classList.add("day_move");
        document.getElementById('32').classList.add("day_move");
        document.getElementById('33').classList.add("to_bottom");
    }
    display_top_task();
    display_lower_tasks();
    display_date();
    console.log(array);
    move_day();
});