Javascript: Questions about using "Const," for lists and objects

Question

Naturally I assumed the "const," keyword meant the value of a variable could not change, and when it comes to integers and strings that seems to be the case. However, today I was watching a video and somebody type the following

const my_list = [];

my_list.push(someValue);

I was surprised to find out that this kind of code actually works, as I was under the assumption that the list would be constant. So my question is: Why? What advantage does declaring the list as constant have if you are just going to change it anyways?

You can no longer do my_list = ['some other array']. Read developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/… — Gabriele Petrioli
– Gabriele Petrioli, Commented Apr 25, 2020 at 17:35
The variable is constant. Not the list itself. The advantage is that you can never end up with losing the reference. For example imagine another piece of code using const the_list = my_list, then the contents of the_list would be updated as long as you'd use my_list.push, but you would "split the timeline" by doing my_list = my_list.concat(...) for example. With const the latter would not be allowed. — CherryDT
– CherryDT, Commented Apr 25, 2020 at 17:37
const doesn't make the actual value immutable, it just means you can't re-assign something to the constant. It's beneficial because it reduces the risk of bugs and unintended side-effects. — Lennholm
– Lennholm, Commented Apr 25, 2020 at 18:21

Gagik · Accepted Answer · 2020-04-25 17:51:17Z

3

When you assign variable with string/number/boolean variable contains the value of string/number/boolean, but then you assign variable with object or array variable contains the address of that object/array in 'memory'.Then you push something in array the value of variable is still same address of array in memory , and that is why you not get error

answered Apr 25, 2020 at 17:51

Gagik

961 silver badge6 bronze badges

Sign up to request clarification or add additional context in comments.

Collectives™ on Stack Overflow

Javascript: Questions about using "Const," for lists and objects

1 Answer 1

Comments

Your Answer

Hot Network Questions

Collectives™ on Stack Overflow

1 Answer 1

Comments

Your Answer

Sign up or log in

Post as a guest

Related