Fix missing docstrings (new PR) (#3740)
* Move documentation for _js into docstring, not a stray comment
* Add missing argument docstrings (and remove non-existent ones)
* Add changelog entry
* updated docstrings
* changelog
* contributors
* changelog
* formatting
* removed _js
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Co-authored-by: Aarni Koskela <akx@iki.fi>
