Most UI frameworks, such as React, operate as if they are informal state machines. Each component is a state/nested state, they have their mount/unmount logic a

Most UI frameworks, such as React, operate as if they are informal state machines. Each component is a state/nested state, they have their mount/unmount logic as onEnter/onExit transitions for the state, most of the event handlers the application cares about will be added or torn down within the context of that state, i.e. onClicks, onSubmit, onKeyPress, onChange, data loaded, etc.