/**
 * Copy the values of all enumerable own properties from one or more
 * source objects to a target object. It will return the target object.
 */
var assign = Object.assign ? Object.assign : function assign(target) {
  if (target === undefined || target === null) {
    throw new TypeError('Cannot convert first argument to object');
  }

  var to = Object(target);
  for (var i = 1; i < arguments.length; i++) {
    var nextSource = arguments[i];
    if (nextSource === undefined || nextSource === null) {
      continue;
    }

    var keysArray = Object.keys(Object(nextSource));
    for (var nextIndex = 0, len = keysArray.length; nextIndex < len; nextIndex++) {
      var nextKey = keysArray[nextIndex];
      var desc = Object.getOwnPropertyDescriptor(nextSource, nextKey);
      if (desc !== undefined && desc.enumerable) {
        to[nextKey] = nextSource[nextKey];
      }
    }
  }

  return to;
}

module.exports = {
  assign: assign
};