find 2nd largest number given array

hubspot_interview_question.js

// second_largest (array of numbers)
// returns 2nd largest number in array
function second_largest(numbers) {
    if(numbers.length < 2){
        return numbers[0];
    }
    var n,
        first_largest  = numbers[0],
        second_largest = numbers[1];

    for (var i = 2, l = numbers.length; i < l; i++) {
        n = numbers[i];
        if (n > second_largest) {
            if (n > first_largest) {
                second_largest = first_largest;
                first_largest = n;
            } else {
                second_largest = n;
            }
        }
    }
    return second_largest;
}


alert(second_largest([6, 0, 1, 2, 3, 4, 5, 7, 8]));