Trying to find factors of a number in JS

Question

I am just starting JS, and understand the concept of finding a factor. However, this snippet of code is what I have so far. I have the str variable that outputs nothing but the

Answer 1

This got me an 85% on Codility (Fails on the upperlimit, over a billion).

Reducing the input by half doesn't work well on large numbers as half is still a very large loop. So I used an object to keep track of the number and it's half value, meaning that we can reduce the loop to one quarter as we work from both ends simultaneously. N=24 becomes: (1&24),(2&12),(3&8),(4&6)

function solution(N) {

    const factors = {};

     let num = 1;  
     let finished = false;
     while(!finished)
     {
         if(factors[num] !== undefined)
         {
             finished = true;
         }
         else if(Number.isInteger(N/num))
         {

          factors[num] = 0;
          factors[N/num]= 0;
         }
        num++
     }

    return Object.keys(factors).length;
}