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Asad Ullah
Asad Ullah

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JavaScript Const re-assignment in Array with full Concepts

Variable Const

As we know that the "const" keyword was included in ES6(2016). The const variable cannot be reassign the value. JavaScript const variables must be assigned a value when they are declared like this...

const firstName = "Sayyed Asad";
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But this is a general rule, always declare a variable with const unless you know that the value will change.
Use const when you declare...

  1. New Array
  2. New Object
  3. New Function
  4. New Regexp

How would be re-assignment of const in an array and what's the reason about that behind the concept of this topic?

const developers = ['Sayyed Asad', 'Nisar', 'Toqeer'];
developers[2] = 'Jonas';


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So, first of all as a good experience in the JavaScript. I should be inform you here is const is manipulate. But I was still able to change one element of the Array here from Toqeer to Jonas.That is only primitive value. But an Array is not a primitive value. And so we can actually always change it so we can mutate it.

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Top comments (2)

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_genjudev profile image
Larson

const is just working as expected.

const arr = [1,2,3]
arr = [0] // Uncaught TypeError: Assignment to constant variable.
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you don't re-assign in your example. You updated an item.

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sayyedasad786 profile image
Asad Ullah

Dear Lars Feldeisen please check the full code in your code and use array using with re-assignment of an array. This is very simple or critical topic for you and I suggest you please discuss this article with your seniors.