Multi-dimension Array reference problem

Question

So currently I have an Array here, and I want to make some modification of the last item and push it back it. Here I have this code: (example is simplified)

var array = [
                 [ [0,1,2], [3,4,5] ]
            ];

//other stuff...

var add = array[0].slice(); //to clone the array (but not working as expected)
add[0][0] = 10;
array.push(add);

console.log(array);

And here's the result

　　　　　　　 enter image description here

As you can see, both the 1st and 2nd item have its first item changed to 10. How can I solve this problem? I have already cloned the array.

Yeah figured it out, you realize the problem is that the objects inside are references not new objects — aaronman, Jul 19 '13 at 04:02

score 5 · Accepted Answer · edited May 23 '17 at 12:03

5

Array.prototype.slice() does shallow copy, so nested array are not copied. You should use deep clone method like this.

edited May 23 '17 at 12:03

Community

1
1

answered Jul 19 '13 at 03:55

Mics

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Ur answer is good but it would be nice if you spoke on the point that the array created by slice is new but the objects inside the original array are not copied but references – aaronman Jul 19 '13 at 04:00
@aaronman Agree. I think "shallow copy" explains it all, doesn't it? – Mics Jul 19 '13 at 04:04

score 1 · Answer 2 · answered Jul 19 '13 at 03:58

Array.prototype.slice() does not clone nested array. you can do something like this particular to your problem

var array = [
                 [ [0,1,2], [3,4,5] ]
            ];

//other stuff...

var add = array[0].slice(); //to clone the array (but not working as expected)
add[0] = array[0][0].slice();
add[0][0] = 10;
array.push(add);

console.log(array);

Multi-dimension Array reference pro­blem

2 Answers2

Multi-dimension Array reference problem