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 * Generate an array of timeslots based on timeinterval
 * Assumption for brevity: 
 * - startTime and endTime are of valid time
 * - startTime will never be later than end time
 * @param  {integer} timeinterval   In mins. Can only accept 15, 30 or 60
 * @param  {string}  startTime      '03:45'. Min - '00:00', Max - '24:00'
 * @param  {string}  endTime        '15:00'. Min - '00:00', Max - '24:00'
 * @return {array}                  ['03:45', ....., '15:00']

function generateTimeslots(timeInterval, startTime, endTime) {
 var validateBookings = function() {
      //Create a date Object using the supplied timeInterval
      var dateInterval = new Date();

        timeSlot = dateInterval;

  var rejectBookings = function() {
    throw('incorrect interval!')        
  //Acceptable time ranges in an array. Validate the supplied interval.
  var timeRange = [15,30,60]; 
  timeRange.includes(timeInterval) ? validateBookings() : rejectBookings();
  //Convert start and end strings into date Objects.
  var splitStart = startTime.split(":")
  var splitEnd = endTime.split(":")
  var startHours = splitStart[0];
  var startMins = splitStart[1]
  var endHours = splitEnd[0];
  var endMins = splitEnd[1]

  //Create Start Time date object
  var startDate = new Date();
  //Create End Time date object
  var endDate = new Date();

//Set the starting point for the time slots

//Set the array to hold the slots
    var finalSlots = [];

//This function validates that the timeslots are all within an acceptable range and fall within the hour.
  var checkHours = function(hours) {

    var validateArray = [];
      //Check to see if the time range is valid (must fall on the hour.
      for (i = 0; i <= hours.length -1; i++) {
          if (hours[i].substr(hours[i].indexOf(":") + 1) != 00 || hours[i].substr(hours[i].indexOf(":") + 1) != 0)
          else {
      return validateArray;

//Calculate the time slots between the start and end timings
  var incrementTimeSlots = function() {
    //Simple loop that pushes the time intervals to an array.
    while((endDate.getTime() + timeInterval) > timeSlot.getTime()) {
        var interval = timeSlot.getHours() + ':' + timeSlot.getMinutes();
        //increment the timeslot & keep the loop going.
        timeSlot.setMinutes(timeSlot.getMinutes() + timeInterval)
    //Check to see if at least one interval falls on the hour
    if (!checkHours(finalSlots).includes('pass')) {
        return('Error: Incorrect time Interval');
    else {
        return finalSlots;
  return incrementTimeSlots();

// console.log(generateTimeslots(5, '00:00', '24:00')); // Error: Can only accept 15, 30, 60
console.log(generateTimeslots(30, '08:45', '10:15')); // Error: Incorrect time interval
console.log(generateTimeslots(15, '08:45', '10:15')); // ['08:45', '09:00', '09:15', '09:30', '09:45', '10:00', '10:15']
console.log(generateTimeslots(15, '13:15', '15:00')); // ['13:15', '13:30', ...., '14:45','15:00']
console.log(generateTimeslots(30, '08:00', '14:00')); // ['08:00', '08:30', '09:00', ....., '13:30', '14:00']
console.log(generateTimeslots(60, '21:00', '24:00')); 
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