How to add a .js file to the Svelte REPL?

Question

In the Svelte REPL it is possible to add a new .svelte file but not a new .js file, but samples exist do have .js files:

Is it possible for end users to do the same?

user_2777805 · Answer

When you add a new file (plus-sign), you need to just type .js at the end of file