index.js
function defaults(object, options) {
  object = object || {};
  for (var i in options) {
    if (undefined === object[i] && options.hasOwnProperty(i)) {
      object[i] = options[i];
    }
  }
  return object;
}
function defaults(object, options) {
  object = object || {};
  for (var i in options) {
    if (undefined === object[i] && options.hasOwnProperty(i)) {
      object[i] = options[i];
    }
  }
  return object;
}
function defaults ( object , options ) { object = object || { } ; for ( var i in options ) { if ( undefined === object [ i ] && options . hasOwnProperty ( i ) ) { object [ i ] = options [ i ] ; } } return object ; }
Extend object if a property is not defined yet
@param {Object} object
@param {Object} options
@returns {Object}
Extend object if a property is not defined yet