Function message_callback_handler 

pub fn message_callback_handler<E: 'static>(
    callback: Option<Rc<dyn Fn()>>,
) -> Option<Rc<dyn Fn(E)>>

Builds the click handler that fires a caller’s message callback.

The event type is a parameter so the DOM-free test suite can drive the handler with a stand-in event; the component always instantiates it with Event.

Arguments

• Option<Rc<dyn Fn()>> - The callback fired by the handler.

Returns

• Option<Rc<dyn Fn(E)>> - The click handler, or None when there is no callback.