## Wednesday, July 22, 2020

### Sum All Primes

From: https://www.freecodecamp.org/learn/javascript-algorithms-and-data-structures/intermediate-algorithm-scripting/sum-all-primes

Intermediate Algorithm Scripting: Sum All Primes

A prime number is a whole number greater than 1 with exactly two divisors: 1 and itself. For example, 2 is a prime number because it is only divisible by 1 and 2. In contrast, 4 is not prime since it is divisible by 1, 2 and 4.

Rewrite sumPrimes so it returns the sum of all prime numbers that are less than or equal to num.

sumPrimes(10) should return a number.

sumPrimes(10) should return 17.

sumPrimes(977) should return 73156.

```function* primesGenerator(qualifierFunc) {
const primes = [2];
yield primes[0];
for (let odd = 3; ; odd += 2) {
if (qualifierFunc && !qualifierFunc(odd)) {
return;
}

if (primes.some(n => odd % n === 0)) {
continue;
}

yield odd;
primes.push(odd);
}
}

function sumPrimes(num) {
return Array.from(primesGenerator(n => n <= num)).reduce((a, b) => a + b);
}

console.log(sumPrimes(10));
console.log(sumPrimes(977));
```

Output:
```17
73156
```