freeCodeCamp Challenge Guide: Where do I Belong

Guide
45

My solution was:

Spoiler Alert! 
function getIndexToIns(arr, num) {

  function sorter(a, b) {
    return a-b;
  }

  function comparator(i) {
    return i >= num;
  }

  let sortedArr = arr.sort(sorter);
  let seekedIndex = sortedArr.findIndex(comparator);
  
  return (seekedIndex == -1 && arr.length == 0) ? 0
        : (seekedIndex == -1 && arr.length > 0) ? arr.length
        : seekedIndex;

}

After passing all the tests I’ve checked solutions proposed here to see how far I was from most elegant one.

My code was similar to the intermediate solution with findIndex method (yay!), but it can handle properly as well the case with getIndexToIns([40, 60, 4, 120], 50), on the contrary to the proposed solution.

Not sure why this code:

Intermediate Solution 
function getIndexToIns(arr, num) {
  // sort and find right index
  var index = arr.sort((curr, next) => curr > next)
    .findIndex((currNum)=> num <= currNum);
  // Returns proper answer
  return index === -1 ? arr.length : index;
}

getIndexToIns([40, 60, 4, 120], 50);

returns 1 though.

Any ideas?