Creates a deep clone of an object.

Use recursion.
Check if the passed object is null and, if so, return null.
Use Object.assign() and an empty object ({}) to create a shallow clone of the original.
Use Object.keys() and Array.prototype.forEach() to determine which key-value pairs need to be deep cloned.

代码片段

const deepClone = obj => {
  if (obj === null) return null;
  let clone = Object.assign({}, obj);
  Object.keys(clone).forEach(
    key => (clone[key] = typeof obj[key] === 'object' ? deepClone(obj[key]) : obj[key])
  );
  return Array.isArray(obj) && obj.length
    ? (clone.length = obj.length) && Array.from(clone)
    : Array.isArray(obj)
    ? Array.from(obj)
    : clone;
};

使用样例

const a = { foo: 'bar', obj: { a: 1, b: 2 } };
const b = deepClone(a); // a !== b, a.obj !== b.obj