# Comparing the performance of recursive and looped factorial function in JavaScript

JavascriptWeb DevelopmentFront End TechnologyObject Oriented Programming

We will be writing two JavaScript functions, the job of both the functions will be to take in a number and return its factorial.

The first function should make use of a for loop or while loop to compute the factorial. Whereas the second function should compute the factorial using a recursive approach.

Lastly, we should compare the times taken by these functions over a large number of iterations.

## Example

Following is the code −

const factorial = (num = 1) => {
let result = 1;
for (let i = 2; i <= num; i += 1) {
result *= i;
}
return result;
}
const factorialRecursive = (num = 1) => {
if(num > 1){
return num * factorialRecursive(num - 1);
}else{
return 1;
}
};
const ITERATIONS = 100000000;
const num = 12;
console.time('Looping Approach');
for(let i = 0; i < ITERATIONS; i++){
factorial(num);
};
console.timeEnd('Looping Approach');
console.time('Recursive Approach');
for(let j = 0; j < ITERATIONS; j++){
factorialRecursive(num);
};
console.timeEnd('Recursive Approach');

## Output

Following is the output on console −

Looping Approach: 886.720ms
Recursive Approach: 6526.203ms

This time taken will vary from machine to machine by the ratio is bound to remain more or less the same.

Published on 10-Dec-2020 08:29:16