Apply Functional Programming to Convert Strings to URL Slugs-What is wrong?

Tell us what’s happening:
The compiler don’t let to pass the test. But everything works properly.

Your code so far

// the global variable
var globalTitle = "Winter Is Coming";

// Add your code below this line
function urlSlug(title) {
 return [...title.toLowerCase().split(/\W+/g)].join('-');
// Add your code above this line

var winterComing = urlSlug(globalTitle); // Should be "winter-is-coming"


Your browser information:

User Agent is: Mozilla/5.0 (Windows NT 10.0; Win64; x64) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/72.0.3626.81 Safari/537.36.

Link to the challenge:

What error are you getting?

urlSlug(" Winter Is Coming") should return “winter-is-coming”.
but it returns …

Seeing your code, I think that it returns