code: function pad(value, length) {
    value = String(value);
    length = length || 2;
  
    while (value.length < length) {
      value = '0' + value;
    }
  
    return value;
  }
docs: Pad 'value' with zeros up to desired 'length'
  @param {String|Number} value
  @param {Number} [length]
  @returns {String}