How to find factorial of a number in JavaScript

To find the factorial of a number in JavaScript, you can use a loop or a recursive function. Here’s an example using both approaches:

1. Using a loop (for loop):

function factorialLoop(n) {
  if (n === 0 || n === 1) {
    return 1;
  } else {
    let factorial = 1;
    for (let i = 2; i <= n; i++) {
      factorial *= i;
    }
    return factorial;
  }
}

console.log(factorialLoop(5)); // Output: 120

2. Using recursion:

function factorialRecursive(n) {
  if (n === 0 || n === 1) {
    return 1;
  } else {
    return n * factorialRecursive(n - 1);
  }
}

console.log(factorialRecursive(5)); // Output: 120

In both approaches, the factorial of a number n is calculated by multiplying all the numbers from 1 to n together. The base case for the recursion is when n is 0 or 1, where the factorial is always 1. The loop iterates from 2 to n, accumulating the factorial value in each iteration. The recursive function calls itself with a decreasing value of n until it reaches the base case.

You can replace the argument (5 in the examples) with any positive integer to calculate the factorial of that number.