Quick Guide: How to Find the Second Largest Element’s Index in JavaScript Arrays

Finding the second largest value index in an array is a common challenge many developers face, especially during coding interviews. In this article, I’ll show you how to implement a JavaScript function to find the index of the second-largest value efficiently.

Problem Statement

Given an array of numbers, we need to find the index of the second-largest value. For example:

const numbers = [12, 35, 1, 10, 34, 1];

In the above example, the largest value is 35 at index 1, and the second largest value is 34 at index 4. So, our function should return 4.

Approach

To solve this problem, we’ll break it down into a few simple steps:

1. Traverse the array to find the largest value.
2. Traverse the array again to find the second-largest value.
3. Return the index of the second largest value.

Solution: JavaScript Function

Let’s jump straight into the code.

Code Implementation

function findSecondLargestIndex(arr) {
  if (arr.length < 2) return -1; // Handle edge case if array has…