Great stuff!

You're using a global var, and it keeps its value between tests. It's in the Troubleshooting guide I told you in my first post ;)

You use split to separate the words, there is an array method to undo that, it's one of these: https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/Array#instance_methods and you already used it in your code, that way, you don't add that space to the end or you could use another string method to get rid of it, your choice.

"test" is a 4 letters word, it's going inside your first if, and you're adding a space to the final string.

Look harder at your first if.

Ive looked over the document you provided me, thanks for that. I still can't understand why my code isn't working. It's saying now ive left a space at the end of the returned string.
Oh well, thanks for trying to help.

Read this: https://docs.codewars.com/training/troubleshooting/ about your code's problem
And this about how to post your code here: https://docs.codewars.com/training/troubleshooting/#post-discourse

expected 'Hey wollef sroirrawThis is a test ' to equal 'This is a test'
//          your function returned this     instead of      this