You can calculate the median of an array of numbers in JavaScript in the following steps:

- Sort the array in ascending order;
- Determine the median, which would be one of the following:
- Element at the middle index if the array has an odd number of elements, or;
- Average of the two elements at the middle indexes if the array has an even number of elements.

For example, you can implement this in the following way:

function median(arr) { // 1: sort array in ascending order const sortedArr = arr.sort(); const middleIndex = arr.length / 2; // 2.1: if odd, return middle element if (arr.length % 2 !== 0) { return arr[Math.floor(middleIndex)]; } // 2.2: if even, return average of two middle elements return (arr[middleIndex - 1] + arr[middleIndex]) / 2; } console.log(median([1, 2])); // 1.5 console.log(median([4, 1, 7])); // 4 console.log(median([3, 7, 5, 1, 8, 9])); // 6 console.log(median([39, 3, 14, 29, 23, 13, 23, 23, 40, 23, 21, 5, 7, 12, 56])); // 23

For arrays with an odd length, rounding down the middle index (i.e. `Math.floor(middleIndex)`

is needed because dividing an odd array length by `2`

would yield a fraction.

This post was published by Daniyal Hamid. Daniyal currently works as the Head of Engineering in Germany and has 20+ years of experience in software engineering, design and marketing. Please show your love and support by sharing this post.