fibonacciRecursive.js

// recursive. output starts at 0
function fib(number) {
    if(number == 0) return 0;    
    if(number == 1) return 1;
    return fib(number - 2) + fib(number - 1);
}

// shorter recursive. output starts at 1
function fibRecursive(n) {
    if(n <= 1) return 1;
    return fibRecursive(n - 2) + fibRecursive(n - 1);
}