show_hint demo appears to do nothing

https://codemirror.net/5/doc/manual.html#addons
points to a demo of the functionality for hints for JavaScript.
On that page: CodeMirror: Autocomplete Demo
it says “ctrl-space to activate autocompletion”
but I click in the editor on a word, say “function”
then delete the last two chars to get “functi”
then type ctrl-space and nothing happens.
I was expecting to see a menu of possible completions
or maybe for it just to complete to “function”.
I must be missing something.
(I’m using the latest Chrome browser on MacOS, running Ventura.)

Anyway, once this is working (or you tell me what I’m doing wrong)
in order to implement this for my CodeMirror application,
do I just have to load the show-hint and javascript-hint addons files,
and that will automatically do the key binding to ctrl-space or
do I need to also bind the functionality (and if so, how?)