function isObject(item) {
  return (
    item &&
    typeof item === "object" &&
    !Array.isArray(item) &&
    Object.getPrototypeOf(item) === Object.prototype
  );
}

export default function mergeDeep(target, ...sources) {
  if (!sources.length) return target;
  const source = sources.shift();

  if (isObject(target) && isObject(source)) {
    for (const key in source) {
      if (isObject(source[key])) {
        if (!target[key])
          Object.assign(target, {
            [key]: {},
          });
        mergeDeep(target[key], source[key]);
      } else {
        Object.assign(target, {
          [key]: source[key],
        });
      }
    }
  }

  return mergeDeep(target, ...sources);
}