JavaScript object property reference problem

Asked Apr 28 '20 at 07:14

Active Apr 28 '20 at 08:58

Viewed 18 times

i make stack2[0].matrix refer to stack1[0].matrix, but after i change stack2[0].matrix, the stack1[0].matrix is changed too. why is this happen? and how can i keep stack1[0].matrix value?

thank you




let Number = function(){
    this.matrix = [
        [1, 2, 3],
        [4, 5, 6]
    ]
}

stack1 = [];
stack2 = [];

stack1.push(new Number);
stack2.push(new Number);
stack2[0].matrix = stack1[0].matrix;
stack2[0].matrix[0][0] = 5;

console.log(stack1[0].matrix);
console.log(stack2[0].matrix);

edited Apr 28 '20 at 08:58

Engineer S. Saad

asked Apr 28 '20 at 07:14

Fariza Adiatma

https://stackoverflow.com/questions/7486085/copy-array-by-value – VLAZ Apr 28 '20 at 07:16
2

`stack2[0].matrix = stack1[0].matrix;` doesn't copy the object itself, it only creates another reference to the object in memory, so if you mutate it at one location, you'll see the mutation elsewhere too – CertainPerformance Apr 28 '20 at 07:16
Overwriting `Number`is probably not the smartest idea. – connexo Apr 28 '20 at 07:25
you should take a look at pointers. both pointers point to the same memory hence the change – EugenSunic Apr 28 '20 at 07:27

JavaScript object property reference problem

0 Answers0