JS 深拷贝

deepClone.js

function deepClone(obj, hash = new WeakMap()) {
  if (obj !== Object(obj) || typeof obj === 'function') return obj;
  if (obj instanceof Set) return new Set(obj);
  if (hash.has(obj)) return hash.get(obj);

  let result;
  if (obj instanceof Date) {
    result = new Date(obj);
  } else if (obj instanceof RegExp) {
    result = new RegExp(obj.source, obj.flags);
  } else if (obj.constructor) {
    result = new obj.constructor();
  } else {
    result = {};
  }

  hash.set(obj, result);
  if (obj instanceof Map) {
    obj.forEach((val, key) => result.set(key, deepClone(val, hash)));
  }

  return Object.assign(
    result,
    ...Object.entries(obj).map(([key, val]) => ({
      [key]: deepClone(val, hash),
    })),
  );
}

const data = {
  a: 1,
  b() {
    console.log(this.a);
  },
  c: new Map([[1, 2], [3, { a: 2 }]]),
  d: new Date('1998'),
};

const copy = deepClone(data);
copy.c.get(3).b = 4;
console.log(copy, data);