sum prime numbers bonfire Challenge

gistfile1.txt

function sumPrimes(num) {
  //create an array of prime numbers up to num
  var primesArray = [];
  
  function isPrime(number) {
    //tests for prime
    //var index = 2;
    var sqrt = Math.sqrt(number);
    
    for (var index=2; index <= sqrt; index++) {
      if (number % index === 0) {
        return false;
      }
      
    }
    return true;
  }
  
  
  
  for (var i=2; i <= num; i++) {
    //test isPrime
    if (isPrime(i)) {
      primesArray.push(i);
    }
    //insert into an array
  }
  
  
  
  //sum the array
  var sum = primesArray.reduce(function(a,b) {
    return a+b;
  });
  
  
  return sum;
}

sumPrimes(10);