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Array with Const

Before we start learning about const with arrays, let's first review what const is and how it works.

Basically the const keyword is used to declare a variable that cannot be reassigned to a new value.

However, when declaring an array with const, the values within the array can still be changed or modified.

For example:

const myArray = [1, 2, 3];
myArray.push(4);
console.log(myArray); // [1, 2, 3, 4]

In this example:

  • We declare a constant myArray and assign it an initial value of [1, 2, 3].
  • We then use the push() method to add the value 4 to the end of the array.
  • Despite being declared with const, myArray can still be modified by adding new elements to it.

Here if we try to reassign the entire array to a new value, we will get an error:

const myArray = [1, 2, 3];
myArray = [4, 5, 6]; // TypeError: Assignment to constant variable.

In this example:

  • We are attempting to reassign myArray to a new value of [4, 5, 6].

  • Since myArray was declared with const, this will result in a TypeError.

info

When using const with arrays in JavaScript, note that the variable cannot be reassigned to a new value.