Loop true list using csom

How do i loop true, items in calender list in SharePoint, right now my code only displays the first value from the list and not the second,

Can someone help me?

function onQuerySucceeded() {

var startCon = listItemCustom + "T" + "08" + ":00" + "Z";
var endCon = listItemtoDate + "T" + "17" + ":00" + "Z";
var dtstartCon = new Date(startCon);
var dtEndCon = new Date(endCon);
var convertUtctoFromtime = new Date(dtstartCon.getTime() + dtstartCon.getTimezoneOffset() * 60 * 1000);
var start = new Date(convertUtctoFromtime);
var convertUtcToTime = new Date(dtEndCon.getTime() + dtEndCon.getTimezoneOffset() * 60 * 1000);
var end = new Date(convertUtcToTime);

var listItemEnumerator = collListItem.getEnumerator();
while (listItemEnumerator.moveNext()) {
    var oListItem = listItemEnumerator.get_current();
    var listEventDate = oListItem.get_item('EventDate');
    var listEventdt = new Date(listEventDate);
    var listEndDate = oListItem.get_item('EndDate');
    var listEventEnddt = new Date(listEndDate);

    var string = [[listEventdt, listEventEnddt]];

    while (end.getTime() >= start.getTime()) {

        var firstnewDate = (start.setTime(start.getTime()));
        var firstNewDt = new Date(firstnewDate);
        var newDate = start.setTime(start.getTime() + 30 * 60 * 1000);
        start = new Date(newDate);

        for (var i = 0; i < string.length; i++) {


            var date = string[i][0];
            var date2 = string[i][1];

         if (firstNewDt.getTime() != date && start.getTime() != date2) {
             alert(firstNewDt + " " + start);
         } else {

             alert("Busy");
         }

    }

    }

}

}