JS 数组和对象的拷贝

var arr1 = [1,2,3,4,5,6]
var arr2 = copyArray(arr1)
function copyArray(arr) {
    let res = [];
    for (let i = 0; i < arr.length; i++) {
        res.push(arr[i])
    }
    return res;
}

var arr = [1,2,3,4,5];
var arr2 = arr.slice(0);
arr[2] = 5;
console.log(arr);
console.log(arr2);

var arr = [1,2,3,4,5];
var arr2 = arr.concat();
arr[2] = 5;
console.log(arr);
console.log(arr2);

var arr = [1,2,3,4,5];
var [ ...arr2 ] = arr;
arr[2] = 5;
console.log(arr);
console.log(arr2);

var obj = {
  name: 'FungLeo',
  sex: 'man',
  old: '18'
}
var obj2 = copyObj(obj)
function copyObj(obj) {
  let res = {}
  for (var key in obj) {
    res[key] = obj[key]
  }
  return res
}

var obj = {
  name: 'test',
  sex: 'man',
  old: '18'
}
var obj2 = JSON.parse(JSON.stringify(obj));

var obj = {
  name: 'FungLeo',
  sex: 'man',
  old: '18'
};
var { ...obj2 } = obj;
obj.old = '22';
console.log(obj);
console.log(obj2);