Fibonacci Number LeetCode solution in JavaScript

1
/**
2
 * @param {number} n
3
 * @return {number}
4
 */
5
// Recursion and memomization approach
6
var fib = function (n, cache = {}) {
7
  if (n <= 0) return 0;
8
  if (n in cache) {
9
    return cache[n];
10
  }
11
  if (n == 1 || n == 2) {
12
    return 1;
13
  }
14
  cache[n] = fib(n - 1, cache) + fib(n - 2, cache);
15
  return cache[n];
16
};
17
//Tabulation approach
18
var fib = function (n) {
19
  const table = new Array(n + 1).fill(0);
20
  table[1] = 1;
21
  for (let i = 0; i <= n; i++) {
22
    table[i + 1] += table[i];
23
    table[i + 2] += table[i];
24
  }
25
  return table[n];
26
};