About an const

Question

const arr=[1,2,3]
arr[0]=5

Q: arr[0]=?
Answer is 5...

Found in a challenge.
Why is the answer 5 and not 1?
I thought const is used to declare something that cannot be changed...am I wrong?

Answer 1

💧Alex Tusinean🔥, DEEPAK

• 'const' stands for constant, it is very similar to 'let'. The only differences are its value cannot be changed and it needs to be initialized where you are declaring it.

const x = 13;
console.log(x); // will print 13
x = 14 // will throw an error

➞ It’s not that in the case of 'const' objects you can change the property of that object - it’s just that you can’t reassign a 'const' variable.

const obj = {
    firstName: "Danijel",
    lastName: "Ivanovic"
};
console.log(obj); // will print the obj object

obj.firstName = "@Dan&Jel";
console.log(obj); // will print the obj object, it has new firstName

Note: you have to initialize a 'const' variable, you can’t keep it uninitialized.

Answer 2

👍You are welcome friend! 😄
I hope it helped you.😉

Answer 3

Danijel Ivanović Thank you!

Answer 4

When you're adding to an array or object you're not re-assigning or re-declaring the constant, it's already declared and assigned, you're just adding to the "list" that the constant points to.

Answer 5

Maybe const prevents you from changing the object alright.

Thus you can't now do const arr=[3, 2, 1];

But you can modify. I think this is because all JS cares is if you modify the id of the object not its value.

Answer 6

Exactly which aspect of the object is constant seems to vary from one language to another, which adds to the confusion.

Answer 7

Adding to Danijel Ivanović I have a detailed blog post on const, let and var variable declarations in javascript, right here on sololearn. check it out!

https://code.sololearn.com/WdauYjg8rOiF/?ref=app

Answer 8

So rather a Java kind of const instead of a C kind of const?

Answer 9

Constant is fix does not change

Answer 10

qraulgo