What is the spread operator ...?

could anyone explain me the spread operator and why needed the function as in the ES6.
(function (){


I don’t really understand the question. Here are two MDN articles.

Thank you for the articles.
I have not understand this operator when it comes to the calling function ?

I’m still not sure what you are asking here, you will have to provide some more context. If this is about a challenge can you please post the link to the challenge.