[Solved] Why my code of last project in JavaScript (words) correctly worked in ideaone, but not worked in SoloLearn?

Question

My code correctly worked in ideaone ( https://ideone.com/yxbykK ) but failed in SoloLearn. What I doing wrong?

My output:
$hehe$hoho$haha$hihi$huhu$ $this$is$awesome$ $lorem$ipsum$dolor$sit$amet$,$consectetur$adipiscing$elit$

My code:
class Add {
constructor(...words) {
this.words = words;
}

print() {
var s = "

Answer 1

in the last test case of obiect z you have added a new element "," which is also apearing in your output.. that is not required

Answer 2

Thank you. After deleting element "," in varible z test was passed.

But why this element was in start code I don't know.