复制
1const cloneDeep1 = (target, hash = new WeakMap()) => {
2  // 对于传入参数处理
3  if (typeof target !== 'object' || target === null) {
4    return target;
5  }
6  // 哈希表中存在直接返回
7  if (hash.has(target)) return hash.get(target);
8
9  const cloneTarget = Array.isArray(target) ? [] : {};
10  hash.set(target, cloneTarget);
11
12  // 针对Symbol属性
13  const symKeys = Object.getOwnPropertySymbols(target);
14  if (symKeys.length) {
15    symKeys.forEach(symKey => {
16      if (typeof target[symKey] === 'object' && target[symKey] !== null) {
17        cloneTarget[symKey] = cloneDeep1(target[symKey]);
18      } else {
19        cloneTarget[symKey] = target[symKey];
20      }
21    })
22  }
23
24  for (const i in target) {
25    if (Object.prototype.hasOwnProperty.call(target, i)) {
26      cloneTarget[i] =
27        typeof target[i] === 'object' && target[i] !== null
28        ? cloneDeep1(target[i], hash)
29        : target[i];
30    }
31  }
32  return cloneTarget;
33}
34