Display date value in array

i am trying to display value from EventDate and Enddate from calender list, this code display like this from 08:00, then next alert to 10:00, and next from 11:00 and next alert to 12:00

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 array1 = new Array(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 < array1.length; i++) {


            var date = array1[i];
            var dt = new Date(date);

        alert(dt);
    }

    }

}

it works fine, like this , but i want to include an if statement inside the for loop

 for (var i = 0; i < array1.length; i++) {


            var date = array1[i];
            var dt = new Date(date);

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

                alert("Busy");
            } 
    }

Like this, but here it only runs one time so it only display 08:00, then next alert to 10:00 but not the second item, any suggestions?