recursive function for fibonacci series in java javascript

1// Recursion way to return Fibonacci numbers
2function recursiveFibonacci(n){
3	// base case
4	if(n === 0) return 0
5  	if(n === 1) return 1
6  
7  	// recursioin base
8  	return recursiveFibonacci(n - 2) + recursiveFibonacci(n - 1);
9}
10recursiveFibonacci(6) // should return 8
11
12//////// and ////////
13
14// Iteration way to return Fibonacci numbers
15function iterativeFibonacci(n) {
16  if (n === 0) return 0;
17  if (n === 1) return 1;
18
19  let previous = 0;
20  let current = 1;
21  for (let i = n; i > 1; i--) {
22    let next = previous + current;
23    previous = current;
24    current = next;
25  }
26  return current;
27}
28
29iterativeFibonacci(6) // should return 8
30
31

1function fibonacci(n) {
2    if (n < 2){
3        return 1;
4    }else{
5        return fibonacci(n-2) + fibonacci(n-1);
6    }
7}
8
9console.log(fibonacci(7));
10//Returns 21
11

1var fib = function(n) {
2  if (n === 1) {
3    return [0, 1];
4  } else {
5    var arr = fib(n - 1);
6    arr.push(arr[arr.length - 1] + arr[arr.length - 2]);
7    return arr;
8  }
9};
10
11console.log(fib(8));

1var fib = function(n) {
2  if (n === 1) {
3    return [0, 1];
4  } else {
5    var arr = fib(n - 1);
6    arr.push(arr[arr.length - 1] + arr[arr.length - 2]);
7    return arr;
8  }
9};
10
11console.log(fib(2));