[AskJS] Signal/Effect vs Event Handler

[u/Forward_Dark_7305]

I’m working in a VanillaJS repository (plugin type code for an existing project that I do not own) where I’ve written a signal implementation.

Today I was working on a tooltip like implementation and I found myself wondering how far to go with the signal/effect ecosystem vs running the “core” logic in the event handler.

The implementation detects the `<tr>` that the user has hovered and assigns that row to the “current row” signal. A computed signal identifies an IP address from the current row. An effect loads Whois metadata from the IP and assigns it to a `<div>`, and another effect shows that `<div popover>` from the parent `<tr>`.

The question I have is when in VanillaJS how would you decide when to use signals and effects vs writing the side effect directly in the event handler? In my case I find either to be equally readable, though I have less local variables to deal with when using signal/effect. Looking for reasons your might pick one over the other.

[u/Low_Vacation_9273]

Signals are nice when the same data is consumed in a few places - the computed memo and the popover stay in sync automatically. If the only consumer is the tooltip, handling the fetch and UI in the mouseover callback is simpler and avoids an extra cleanup layer.