JSFiddle - React, Tailwind, and code Playground

JavaScript

function addMinutes(time, minutes) {
  var date = new Date(new Date('01/01/2015 ' + time).getTime() + minutes * 60000);
  var tempTime = ((date.getHours().toString().length == 1) ? '0' + date.getHours() : date.getHours()) + ':' +
    ((date.getMinutes().toString().length == 1) ? '0' + date.getMinutes() : date.getMinutes()) + ':' +
    ((date.getSeconds().toString().length == 1) ? '0' + date.getSeconds() : date.getSeconds());
  return tempTime;
}

var starttime = "09:50:00";
var interval = "10";
var endtime = "10:50:00";
var timeslots = [starttime];


while (starttime != endtime) {
	
  starttime = addMinutes(starttime, interval);
  timeslots.push(starttime);

}
alert(timeslots);