讲一下深浅拷贝

浅拷贝

  arr.slice();
  [].concat();
  Array.from();
  //展开运算符
  const Newlist = [...oldlist];
  map/filter/reduce/object.assign

深拷贝

      const list = [{henan:'jiayou'}];
      const listcopy = JSON.parse(JSON.stringify(list))