Step 1

The first step in writing the find-median-array function is to sort the array. Javascript provides a built-in sort() function which can be used. For example, we can sort an array numbers as follows:

numbers.sort((a, b) => a - b);

This will sort the array in increasing order. We subtract b from a to ensure the function sorts correctly.

Step 2

Next, we need to find the middle of the array. As arrays in Javascript are zero-indexed, it means that the first element is considered as the 0th element. We can get the middle index by dividing the length of the array by two. If the number of elements in the array is odd, we will get a fraction, and we can round down to the nearest whole number using Math.floor(). For example:

let middleIndex = Math.floor(numbers.length / 2);

Step 3

Then, we need to check if the length of the array is even or odd. If it's even, we need to get the average of the two middle numbers. If it's odd, the middle number is the median. We can use the remainder operator % to check if the length is odd or even:

if (numbers.length % 2 === 0) {
    // get average of two middle numbers
} else {
    // middle number is the median
}

Step 4

If the length of the array is even, we need to get the average of the two middle numbers. The second middle number is at the middleIndex, and the first middle number is the previous index. We can get the average as follows:

let median = (numbers[middleIndex] + numbers[middleIndex - 1]) / 2;

Step 5

If the length is odd, the median is the middle number, and we can get it directly from the array:

let median = numbers[middleIndex];

Conclusion

The complete function to find the median of an array can be implemented as follows:

function findMedian(numbers) {
    numbers.sort((a, b) => a - b);
    let middleIndex = Math.floor(numbers.length / 2);
    if (numbers.length % 2 === 0) {
        return (numbers[middleIndex] + numbers[middleIndex - 1]) / 2;
    } else {
        return numbers[middleIndex];
    }
}

This function first sorts the array, then it calculates the middle index. Depending on the length of the array, it either calculates the average of two middle numbers (for even length) or returns the middle number (for odd length).