Simple Javascript function to convert to timeAgo.js

Calculate the time difference for javascript date objects in years, months, days, hours, minutes and seconds. Whether they are in the future or in the past. The function accounts for all very easily. Since this is a lightweight function you can easily use this as part of any application, without incurring much overhead.
github

Code

var timeAgo = function(date) {
  var d = new Date();
  var UTCsecondsNow = (d.getTime() + d.getTimezoneOffset() * 60 * 1000);
  var UTCseconds = (date.getTime() + date.getTimezoneOffset() * 60 * 1000);
  var diff = UTCsecondsNow - UTCseconds;
  var tense = 'ago';
  if (diff < 0) {
    tense = 'later';
    diff = Math.abs(diff);
  }
  if (diff === 0) return 0;
  // 365.25 * 24 * 60 * 60 * 1000
  var years = singular(Math.round(diff / 31557600000), 'Year');
  if (years)
    return years + tense;
  var months = singular(Math.round(diff / 2592000000), 'Month');
  if (months)
    return months + tense;
  var days = singular(Math.round(diff / 86400000), 'Day');
  if (days)
    return days + tense;
  var hours = singular(Math.round(diff / 3600000), 'Hour');
  if (hours)
    return hours + tense;
  var mins = singular(Math.round(diff / 60000), 'Minute');
  if (mins)
    return mins + tense;
  var secs = singular(Math.round(diff / 1000), 'Second');
  if (secs)
    return secs + tense;
};

var singular = function(num, str) {
  if (num > 1) {
    if (num === 1)
      return '1 ' + str + ' ';
    else
      return num + ' ' + str + 's ';
  }
  return '';
};

Usage

timeAgo( new Date('2016-12-04T11:45:00.000Z') )

Output

10 Months ago

Demo