code: function minutesToOffsetString(minutes) {
    var t = String(Math.abs(minutes / 60)).split('.');
    var H = pad(t[0]);
    var m = t[1] ? parseInt(t[1], 10) * 0.6 : 0;
    var sign = minutes < 0 ? '-' : '+';
  
    return '' + sign + H + ':' + pad(m);
  }
docs: Convert 'minutes' to offset string
  @param {Number} minutes
  @returns {String}