Using the Rest Operator for Array Destructuring in JavaScript – Asked in an Epam Interview

Understanding the Code Step by Step

The given JavaScript snippet utilizes array destructuring and the rest operator (...) to extract values from an array into separate variables. Let’s break it down carefully.

Step 1: Declaring an Array

const numbers = [1, 2, 3, 4, 5];

Here, numbers is an array containing five elements:

[1, 2, 3, 4, 5]

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Step 2: Array Destructuring

const [x, ...y] = numbers;

This line uses array destructuring to assign values from numbers into separate variables:

• x gets the first element of the array.
• y collects the remaining elements as an array using the rest operator (...).

So, that

x → 1 and y → [2,3,4,5]

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Deep Dive into the Rest Operator (...y)

The rest operator (...) is used to collect all remaining elements into an array. It doesn’t take the first element but only collects the rest.

⚡ Key Points to Remember:

1. The rest operator always returns an array.
2. It must be the last element in destructuring.

The destructuring syntax along with the rest operator makes JavaScript cleaner and more readable. It allows developers to extract parts of arrays efficiently and work with them flexibly.

So, the next time you need to separate the first item from an array and collect the remaining ones, you know exactly how to do it!

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✔ Final Answer:

B) 1 [2, 3, 4, 5]

This question appeared in the Epam 2nd round of interview, testing the candidate’s knowledge of array destructuring and the rest operator in JavaScript.