Answer to a random interview question

gistfile1.txt

function add1(array, val, n) {
    var iter = 0,
        end = array.length,
        count = (n) ? n : -1,
        multiple = 1;
    
    if(n < 0) {
        iter = array.length - 1;
        end = 0;
        multiple = -1;
    }
    while(iter !== end && count) {
        if(array[iter] === val) {
            array[iter]++;
            count--;
        }
        iter += multiple;
    }
    return array;
}