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Recursion for Coding Interviews in JavaScript

Reverse an Array

Explore how to reverse an array using recursion in JavaScript by breaking the problem into smaller parts. Understand the base cases and recursive approach to flip the array elements. This lesson will help you apply recursion to arrays and prepare for interview questions involving recursive array manipulation.

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What does “Reverse an Array” mean? #

Our task is to flip the elements of the array, meaning we will make the first element of the array the last element, the second element the second last element, and so on.

Reversing an array.
Reversing an array.

Implementation #

Javascript (babel-node)
function reverse(array) {
  // Base case1
  if (array.length == 0) { // If we encounter an empty array, simply return an empty array
    return [];
  }
  
  // Base case2
  else if (array.length == 1) { // Reversing an array of size 1 returns the same array
   return array;
  }
  // Recursive case
  return [array[array.length - 1]].concat(reverse(array.slice(0, array.length - 1)));
  // The first part is storing the last element to be appended later
  // The second part is calling another instance of the same function with the last element removed
}
// Driver Code
array = [1, 2, 3, 4];
console.log(reverse(array));

Explanation

In the code snippet above, (line number 13) ...