Moment.js Sandbox

HTML

<script src="//cdnjs.cloudflare.com/ajax/libs/moment.js/2.2.1/moment.min.js"></script>

JavaScript

const
  endTime = "23:07",
  startTime = "22:07",
  format = 'HH:mm';

console.log(moment.utc(moment(endTime, format) - moment(startTime, format)).format(format));