Sum all the prime numbers up to and including the provided number. A prime number is defined as a number greater than one and having only two divisors, one and itself. For example, 2 is a prime number because it's only divisible by one and two. The provided number may not be a prime.

sum-all-primes.js

function sumPrimes(num) {
  var ints = [2]; //array to hold prime numbers
  
  //function to test if a number is a prime
  function isPrime(test){
    
    for(var i = 2; i < test; i++){
      
      if(test % i == 0){ //if there's no remainder it's not a prime
        return false; //not a prime number
      }
    }
    return true;
  }
  //get all numbers below num that are prime and push to the array
  for(var j = 3; j <= num; j++){
    
    if( isPrime(j) ){
      ints.push(j);
    }
  }
  //reduce the array to a single total by adding all prime numbers
  var sumPrimes = ints.reduce(function(total, current){
    return total + current;
  });
  return sumPrimes;
}

sumPrimes(10);