On “some event” (some component/Store changes), I want to do something client-side (change document.title). I don’t want to return anything anywhere.
Do I have to? 
Hello @stdedos,
Yes, currently you have to return an output, but it doesn’t have to be anything meaningful. It can be to an id of the component and just say:
return window.dash_clientside.no_update
but that … won’t “damage” the component, right?
Can I target … root-content?
Which “property”?
No, it will not do anything to the component, as long as you send back no_update.
Can there be a small mention/example here? Clientside Callbacks | Dash for Python Documentation | Plotly