json数组对象引用赋值让我感到困惑

Question

<script>
 var arr = [{"val":0},{"val":1},{"val":2},{"val":3},{"val":4},{"val":5}];
 var arrCopy = [];

 for(var i=0; i < arr.length; i++){
  var tmp = arr[i];
  arrCopy.push(tmp);
 }
 for(var j=0; j < arrCopy.length; j++){
   arrCopy[j].val = arrCopy[j].val+1;

 }
  console.log("arr:", arr);        //resullt: [{"val",1},{"val",2},{"val",3},{"val",4},{"val",5},{"val",6}]
  console.log("arrCopy", arrCopy);//resullt: [{"val",1},{"val",2},{"val",3},{"val",4},{"val",5},{"val",6}]
</script>

1. 为什么他们打印相同的阵列？这让我感到困惑？
2. arrCopy刚刚获得arr的参考？不是价值的副本吗？
3. 我什么时候可以得到（arr）价值副本而不是参考？

Answer 1

你的语法中只有一个小错误;而不是在每个{"val",0}地图中使用逗号，而是使用冒号：{"val":0}。因此，请将arr更改为

var arr = [{"val":0},{"val":1},{"val":2},{"val":3},{"val":4},{"val":5}];

通过这样做，你说的是从"val"到冒号右边的数字的映射。

Answer 2

问题是当你说

时

tmp = arr[i] // it's just a reference of {"val":0} to tmp not a copy.

更好地做到这一点

var tmp = {};
tmp.val = arr[i].val;