JSFiddle - React, Tailwind, and code Playground

JavaScript

/**
 * Finds the middle item of an array.
 * 
 * @param {Array} arr - Where to look
 * @return {any} The middle item of the array; could be undefined
 */
function findMiddle(arr) {
  if (arr.length === 0) return undefined;

  let middle = Math.floor(arr.length / 2);
  if (arr.length % 2 === 0) {
    return arr[middle - 1];
  } else {
    return arr[middle];
  }
}

const array = [1, 2, 3, 4, 5];
const middle = findMiddle(array);
alert("Middle is " + middle);