Spinal Tap Case Whats's the promlem with the code?

Tell us what’s happening:

just tested it on codepen, and this code passes al the tests, while FCC compilator keeps saying that i dont pass some chalengies. What’s wrong?

Your code so far

function spinalCase(str) {
  // "It's such a fine line between stupid, and clever."
  // --David St. Hubbins
  let newArr=str.toLowerCase()
  return newArr;

spinalCase('This Is Spinal Tap');

Your browser information:

User Agent is: Mozilla/5.0 (Windows NT 10.0; Win64; x64; rv:62.0) Gecko/20100101 Firefox/62.0.

Link to the challenge:

This doesn’t pass 3 of the tests.
“thisIsSpinalTap”, “The_Andy_Griffith_Show” & “AllThe-small Things”

As 2 don’t contain a non-alphanumerical characters and \W does not select underscores.
Check the hints, there’s some good suggestions there on what logic to follow

yep, already passed the task, thats just my carelessness. Also Marked the post to be deleted, cuz i dont have the rights to delete it) was very self-confident to guess that the compilator is wrong)