findSecondLargestElement()

Step 1: Initialize Variables

First, we must declare two variables, max and secondMax, which will store the maximum and second maximum values in the given array respectively. Initially, set max and secondMax both to the smallest numerical value possible by using the built-in Number.MIN_SAFE_INTEGER property.

let max = Number.MIN_SAFE_INTEGER;
let secondMax = Number.MIN_SAFE_INTEGER;

Step 2: Iterating Over the Array

To find the maximum and second maximum values, we have to iterate over each element of the array. For that, we can use a for loop.

for(let i = 0; i < arr.length; i++) {
    // Comparison logic will go here
}

Step 3: Updating Maximum and Second Maximum

Inside our loop, we need to compare the current array element with max and secondMax and update these variables accordingly. If the current element is greater than max, then max and secondMax both should be updated. If it's not greater than max but greater than secondMax, only secondMax needs to be updated. If it's not greater than either, no change is required.

if(arr[i] > max) {
    secondMax = max;
    max = arr[i];
} else if(arr[i] > secondMax && arr[i] < max) {
    secondMax = arr[i];
}

Step 4: Handle Special Cases

We need to handle special cases where all elements in the array are the same or where there is only one element. In these cases, there is no second maximum value.

if(secondMax === Number.MIN_SAFE_INTEGER) {
    return 'No second maximum value';
} else {
    return secondMax;
}

Step 5: Putting It All Together

Finally, let's combine all the above steps into a single function to find the second largest element in an array.

function findSecondLargest(arr) {
    let max = Number.MIN_SAFE_INTEGER;
    let secondMax = Number.MIN_SAFE_INTEGER;
    for(let i = 0; i < arr.length; i++) {
        if(arr[i] > max) {
            secondMax = max;
            max = arr[i];
        } else if(arr[i] > secondMax && arr[i] < max) {
            secondMax = arr[i];
        }
    }
    if(secondMax === Number.MIN_SAFE_INTEGER) {
        return 'No second maximum value';
    } else {
        return secondMax;
    }
}

And there you have it! A function that returns the second largest element in a given array.