understanding fibonacci algorithm javascript code example

Example 1: how to generate a fibonacci sequence in javascript

// declare the array starting with the first 2 values of the fibonacci sequence
    let fibonacci = [0,1];
    
    function listFibonacci(num) {
    // starting at array index 1, and push current index + previous index to the array
        for (let i = 1; i < num; i++) {
            fibonacci.push(fibonacci[i] + fibonacci[i - 1]);
        }
        console.log(fibonacci);
    }
    
    listFibonacci(10);

Example 2: javascript fibonacci example

// number fibonnaci to array format
function fibonacci(nums) {
  
  let fib = [0, 1];
  let data = [];
  
  for(let i = 2; i <= nums; i++) {
    fib[i] = fib[i - 1] + fib[i - 2]; 
    data.push(fib[i]);
  }
  
  return data;
}