Check if a value exists in an array and get the next value JavaScript

We are required to write a JavaScript function that takes in an array of literals as the first argument and a search string as the second argument.

The function should search the array for that search string. If that string exists in the array, we should return its next element from the array, otherwise we should return false.

Example

const arr = ["", "comp", "myval", "view", "1"];

const getNext = (value, arr) => {
    const a = [undefined].concat(arr);
    const p = a.indexOf(value) + 1;
    return a[p] || false;
};

console.log(getNext('comp', arr));
console.log(getNext('foo', arr));

Output

The output in the console will be:

myval
false

How It Works

The function works by creating a new array with undefined at the beginning, then concatenating the original array. This handles the edge case where we search for the first element - its "previous" element becomes undefined, so the next element calculation works correctly.

Alternative Approach

Here's a more straightforward implementation without array concatenation:

const getNextSimple = (value, arr) => {
    const index = arr.indexOf(value);
    if (index !== -1 && index 

Output

myval
false
false


Comparison

Conclusion

Both approaches effectively find the next value in an array. The index-checking method is more readable and explicit about edge cases, while the concatenation method is more concise but requires understanding the clever array manipulation.