Base Case and Recursive Case

Every recursive function must have at least one base case (a condition that stops the recursion) and one recursive case (where the function calls itself). The base case prevents infinite recursion and stack overflow.

function factorial(n) {
  // Base case
  if (n <= 1) return 1;
  // Recursive case
  return n * factorial(n - 1);
}
console.log(factorial(5)); // 120