JS implementation of Fibonacci sequence

Fibonacci sequence ：0、1、1、2、3、5、8、13、21、34、…… In Mathematics , The Fibonacci sequence is defined recursively as follows ：F(0)=0,F(1)=1, F(n)=F(n - 1)+F(n - 2)（n ≥ 2,n ∈ N*）

 //  Use for loop 
 function fibonacci(n) {
   let fibo = [1,1]
   let a = 1;
   let b = 1;
   for (let index = 0; index < n; index++) {
    [b, a] = [a, a+b]
      fibo.push(a)              
    }
    return fibo.toString()
 }
 console.log(fibonacci(6))
 // 1,1,2,3,5,8,13,21
 
//  Use while loop 
function fibonacci2 (n) {
	let nums = [1]
	let count = 1;
	let prev = 0;
	let curr = 1;
	if (n == 1) {
		return [0]
	}
	while (count < n - 1) {
		curr += prev;
		prev = curr - prev;
		nums.push(curr);
		count ++;
	}
	nums.unshift(0);
	return nums
}
console.log(fibonacci2(6));
// [0, 1, 1, 2, 3, 5]

//  Using recursion 
 function fibonacci3(n) {
   if (n < 2) return n
    return fibonacci2(n-1) + fibonacci2(n-2)
 }

 let ff = []
 for (let index = 0; index < 6; index++) {
    ff.push(fibonacci3(index))
 }
 console.log(ff)
 // [0,1,1,2,3,5]