const arr = [10, 20, 30, 5]

function secondLargest(){
    let largestNumber = 0;
    let secondLargest = 0;
    
    for(const num of arr){
        if(num > largestNumber){
            secondLargest = largestNumber;
            largestNumber = num
        }
    }
    return secondLargest;
}

const result = secondLargest(arr);
console.log(result)