# Find the prime factors of a number in JavaScript

The **prime factors** of a number are the prime numbers that divide the number exactly. An easy way to find the prime factors of a number is using trial division, which is a simple algorithm that checks each possible prime factor in order.

Implementing the algorithm is straightforward. You can use a `while`

loop to **iterate** over all possible prime factors, starting with `2`

. If the current factor, `f`

, exactly divides `n`

, add `f`

to the factors array and divide `n`

by `f`

. Otherwise, increment `f`

by one.

const primeFactors = n => { let a = [], f = 2; while (n > 1) { if (n % f === 0) { a.push(f); n /= f; } else { f++; } } return a; }; primeFactors(147); // [3, 7, 7]