Question Algorithm Challenge Guide "Sum All Primes" Solution

[meanyMina]

Hello!
Thank you for your time reading this.

After I solved the problem, I want to check other’s good solutions.
I have question after I read this solution.
First, I understood the logic of the solution.

• Make function to check if the number is prime number-> if the num is prime number, it will add to the result. if not, i will not.

However, how the result sum up all the prime numbers?
I cannot find the code for adding up.

Please explain which point I am missing.
Thank you in advance.

Continuing the discussion from freeCodeCamp Algorithm Challenge Guide: Sum All Primes:

@camperbot

Intermediate Code Solution:

function sumPrimes(num) {
  // function to check if the number presented is prime
  function isPrime(number){
      for (i = 2; i <= number; i++){
          if(number % i === 0 && number!= i){
          // return true if it is divisible by any number that is not itself.
             return false;
          }
       }
       // if it passes the for loops conditions it is a prime
      return true;
  }
  // 1 is not a prime, so return nothing, also stops the recursive calls.
  if (num === 1){
    return 0;
  }
  // Check if your number is not prime
  if(isPrime(num) === false){
  // for non primes check the next number down from your maximum number, do not add anything to your answer
    return sumPrimes(num - 1);
  }

  // Check if your number is prime
  if(isPrime(num) === true){
  // for primes add that number to the next number in the sequence through a recursive call to our sumPrimes function.
    return num + sumPrimes(num - 1);

[snowmonkey]

SumPrimes is “recursive,” meaning it calls itself repeatedly.In the return statement is where the summing happens - nonprimes simply pass the next iteration, while primes add themselves to a possibly deeply nested math expression.

Doesn’t seem it would be very efficient though.