实现Object.assign()

[AlexZ33]

简单版本

exports.merge = function merge(origin, opts) {
  if (!opts) return origin;
  const res = {};

  const originKeys = Object.keys(origin);
  for (let i = 0; i < originKeys.length; i++) {
    const key = originKeys[i];
    res[key] = origin[key];
  }

  const keys = Object.keys(opts);
  for (let i = 0; i < keys.length; i++) {
    const key = keys[i];
    res[key] = opts[key];
  }
  return res;
};