Merging two arrays in a unique way in JavaScript

We are required to write a JavaScript function that takes in two arrays and merges the arrays taking elements alternatively from the arrays.

For example

If the two arrays are ?

const arr1 = [4, 3, 2, 5, 6, 8, 9];
const arr2 = [2, 1, 6, 8, 9, 4, 3];

Then the output should be ?

[4, 2, 3, 1, 2, 6, 5, 8, 6, 9, 8, 4, 9, 3]

Using Index-Based Approach

The code for this will be ?

const arr1 = [4, 3, 2, 5, 6, 8, 9];
const arr2 = [2, 1, 6, 8, 9, 4, 3];

const mergeAlternatively = (arr1, arr2) => {
    const res = [];
    for(let i = 0; i 

[
  4, 2, 3, 1, 2, 6,
  5, 8, 6, 9, 8, 4,
  9, 3
]


Using Math.max() for Different Array Lengths

Here's an approach that handles arrays of different lengths better:

const arr1 = [1, 2, 3, 4];
const arr2 = [5, 6, 7, 8, 9, 10];

const mergeAlternatively = (arr1, arr2) => {
    const res = [];
    const maxLength = Math.max(arr1.length, arr2.length);
    
    for(let i = 0; i 

[1, 5, 2, 6, 3, 7, 4, 8, 9, 10]


How It Works

The first approach uses modulo operator to determine which array to pick from:

• Even indices (0, 2, 4...) take from arr1 at positions (0, 1, 2...)
• Odd indices (1, 3, 5...) take from arr2 at positions (0, 1, 2...)

The second approach iterates through both arrays simultaneously, adding elements when available.

Comparison

Conclusion

Both approaches merge arrays alternately. Use the Math.max method for arrays of different lengths, or the index-based approach for equal-length arrays with simpler logic.