How exactly does this code run?

1

Hello guys~
I was doing the sum up the prime task and saw a code that is easy to read and to understand.
However, I have a question regarding the for loop part.

Below is the correct one
`function isPrimes(num)
{
for (var i=2; i < num; i++)
{
if (num % i=== 0) {
return false;
} // if
}//forloop

return true ;

}//isPrimes

function sumPrimes(num){
var sum = 0;
for (var i=2 ; i <=num ; i++){
if(isPrimes(i)){
sum += i;
}
}
return sum;
}
sumPrimes(10);
`

When I tried to do write it myself, I put return trueinside the for loop, like this
`function isPrimes(num)
{
for (var i=2; i < num; i++)
{
if (num % i === 0)
{return false;
} // if
else{
return true ;
}
}//forloop

}//isPrimes
`

The second function remains the same but the result ofsumPrimes(10) became 24 instead of 17.
Can anyone explain the logic for me?? Will be very appreciated. Thanks in advance!

2

what is this is_number ? i dont see any variable is_number and can you please share the challenge link so that we can test and see what going on

3

Sorry it’s a mistake.
should be
if (num % i === 0) { return false;}

and here is the link.
https://www.freecodecamp.org/challenges/sum-all-primes

Thank you

4

i just checked it working fine.

    if (num % is_number === 0) {

    return false;

It was the mistake. now its working fine.
17

Screenshot_19

5

My result is 24

image
image984×472 25.7 KB

:confused:

6

eliminate the else section.. and place return true in the isPrimes function scope .
Cause right now its not returning properly from the function.its stuck in if statement.
so just return true in function scope. like this :

function isPrimes(num){
  for (var i=2; i < num; i++){
  if (num % i=== 0) {
  return false;
  } // if
}//forloop
return true ;
}