Technically in React, the reactive callback is still the event handler. It's a two-step process where your event handler is evaluated first, then re-evaluates the component tree which changed as a result of the handler. In your JSFiddle example, if you modify `onChange` to print a console log instead of setting state, you'll see that it doesn't run the component function again.

So really, the key difference between React and Vue is that your function component is not the setup, it's the template.

I don't know if I'd consider that the reactive callback because there's no change in state if I only put the `console.log` in `onChange`. The point of the reactive callback is to be invoked on a change in state and in this case, that is the component function would you agree?

In Vue, for example, when I set up a `watch`, the change in state only invokes the callback that is wired to the state. In React, the entire component function is invoked again on a change of state.

Yeah that's a pretty good way of putting it. In Vue et al, the script tag is a constructor and the template is a render function. In react, you just write a render function and use hooks to define stuff that otherwise would have been in the constructor.