# JavaScript Challenge - Sum of Prime Factors

This community-built FAQ covers the “Sum of Prime Factors” code challenge in JavaScript. You can find that challenge here, or pick any challenge you like from our list.

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Hi All,

Here is my solution to this challenge:

``````function sumOfPrimeFactors(n) {
let factorsArray = [];
for (let i = 1; i <= n; i++) {
if (n % i == 0) {
factorsArray.push(i);
}
}

//now we have the factors array
//we need to filter the prime numbers from the array

let primeFactorsArray = [];
factorsArray.forEach(factor => {
let factorCounter = 0;
for(let i = 1; i <= factor; i++) {
if (factor % i == 0) {
factorCounter++;
}
}
if (factorCounter == 2) {
primeFactorsArray.push(factor);
}
});

//now we have an array of prime factors only
//we just need to find the sum of them all

let sum = 0;
primeFactorsArray.forEach(factor => {
sum += factor;
});
return sum;
}

console.log(sumOfPrimeFactors(91));

// Leave this so we can test your code:
module.exports = sumOfPrimeFactors;
``````
``````function sumOfPrimeFactors(n) {
let sum = 0;
primeLoop:for(let i = 2; i <= n; ++i){
if(n % i != 0) continue;
const s = Math.sqrt(i);
if(Number.isInteger(s)) continue;
for(let j = 2; j < s; ++j)
if(i % j == 0)
continue primeLoop;
sum += i;
}
return sum;
}

module.exports = sumOfPrimeFactors;
``````
``````const _ = require('lodash');

function sumOfPrimeFactors(n) {

function isPrime(num) {
for (let i = 2; i * i <= num; i++) {
if (!(num % i)) return false;
}
return num > 1;
}

return _.range(2, n + 1)
.filter(x => isPrime(x) && !(n%x))
.reduce((total, element) => total + element, 0)
}

console.log(sumOfPrimeFactors(91));
// Leave this so we can test your code:
module.exports = sumOfPrimeFactors;
``````
``````function sumOfPrimeFactors(n) {

let sum = 0;

for (let num = 2; num <= n; num++){
let isPrime =  true;

for (let i = 2; i < num; i++) {
if (num % i === 0) {
isPrime = false;
}
};

if (isPrime === true) {
if (n % num === 0) {
sum += num;
}
}
}

return sum;
};

console.log(sumOfPrimeFactors(91));

// Leave this so we can test your code:
module.exports = sumOfPrimeFactors;
``````
``````function sumOfPrimeFactors(n) {
function isPrime(n) {
for (let j = 2; j <= Math.sqrt(n); j++) {
if (n % j === 0) return false;
}
return true;
}
if (n === 1) return 0;
if (isPrime(n)) return n;
const primeFactors = new Set();
for (let i = 2; i <= Math.sqrt(n); i++) {
if (n % i !== 0) continue;
[i, n / i].forEach((factor) => {
if (!isPrime(factor)) return;
});
}
let sum = 0;
primeFactors.forEach((item) => (sum += item));
return sum;
}
``````
``````function sumOfPrimeFactors(num) {
let sum = 0;
for(let i = 2; i <= num; i++) {
if(isPrime(i)){
if(num % i === 0)
sum += i
}
}
return sum
}
function isPrime(num) {
if(num === 0 || num === 1)
return false
if(
num === 2 ||
num === 3 ||
num === 5 ||
num === 7
) return true
if(
num % 2 === 0 ||
num % 3 === 0 ||
num % 5 === 0 ||
num % 7 === 0
) return false

return true
}

// Leave this so we can test your code:
module.exports = sumOfPrimeFactors;
``````
``````function sumOfPrimeFactors(n) {
let primes =[];

for(let i=2; i<=n;i++){
let j=0;
while(j<primes.length & i%primes[j]!=0){
j++;
}
if(j==primes.length){
primes.push(i);
}
}

let sum = 0;
let j=0;

while(j<primes.length ){
sum += (n%primes[j]) ==0 && primes[j];
j++;
}

return sum;
}

// Leave this so we can test your code:
module.exports = sumOfPrimeFactors;
``````