浅拷贝的几种方法[浅拷贝不能深层次拷贝]

let hd = {
      name: '你好啊',
      year: 12312
    }
    // 浅拷贝的几种方法
    let obj = { ...hd }
    obj.name = '132'
    console.log(obj);//{name: '132', year: 12312}
    console.log(hd);//{name: '你好啊', year: 12312}
方法2
   let obj = Object.assign({}, hd)
    obj.name = 'hello'
    console.log(obj);//{name: 'hello', year: 12312}
    console.log(hd);//{name: '你好啊', year: 12312}

深拷贝

 案例1
 let hd = {
      name: 'hello',
      year: 999,
      user: {
        name: "word"
      }
    }
    function copy(object) {
      let res = {}
      for (const key in object) {
        res[key] = typeof object[key] == 'object' ? copy(object[key]) : object[key]
      }
      return res
    }
    let data = copy(hd)
    data.user.name = 'hello word'
    console.log(JSON.stringify(data, null, 2));
    console.log(JSON.stringify(hd, null, 2));
/*
{
  "name": "hello",
  "year": 999,
  "user": {
    "name": "hello word"
  }
}
index.html:34 {
  "name": "hello",
  "year": 999,
  "user": {
    "name": "word"
  }
}
*/
案例2
 let hd = {
      name: 'hello',
      year: 999,
      user: {
        name: "word"
      },
      arr: [123, 456]
    }
    function copy(object) {
      let res = object instanceof Array ? [] : {}
      for (const [k,v] of Object.entries(object)) {
        res[k] = typeof v== 'object' ? copy(v) : v
      }
      return res
    }
    let data = copy(hd)
    data.arr.push(789)
    console.log(JSON.stringify(data, null, 2));
    console.log(JSON.stringify(hd, null, 2));
/*
{
  "name": "hello",
  "year": 999,
  "user": {
    "name": "word"
  },
  "arr": [
    123,
    456,
    789
  ]
}
index.html:54 {
  "name": "hello",
  "year": 999,
  "user": {
    "name": "word"
  },
  "arr": [
    123,
    456
  ]
}
*/