Autocomplete for JavaScript is only partial?

Autocomplete for JavaScript does not seem to work very well, and I’m wondering if I’m missing something. In the case of something simple, such as:

document.querySelectorAll(‘a’).classList.add(‘myclass’);

‘document’ will autocomplete
‘querySelectorAll’ will autocomplete but…
‘classList’ will NOT autocomplete and
‘add’ will NOT autocomplete either

Changing the syntax setting seems to have no effect on this behavior. Does anyone understand this? Can you explain it to me?

Thanks much!