js 深度复制deepClone

function isObject(obj) {
  return typeof obj === 'object' && obj != null;
}

const deepClone =(source, hash = new WeakMap())=>{

  if(!isObject(source)) return source;

  if(hash.has(source)) return has.get(source)

  const target = Array.isArray(source) ? [] : {};

  hash.set(source, target);

  for( key in source){

    if(Object.prototype.hasOwnProperty.call(source, key)){

    target[key] = deepClone(source[key], hash)

  }

}

return target;

}