Event.md

Event Object

An event object is created at the time of emit. It is passed to each listener. Listeners can modify it.

emit() returns this event object.

Event object can be an instance of Event or child of Event.

type: string

Type of event.

data: any

The data that has been linked with listener (data argument of add()).

results: any[]

The list of listeners return values.

stopPropagation(): void

Calling this function completes the bypass listeners.

isPropagationStopped(): boolean

Checks if stopPropagation() has been called.

preventDefault(): void

Asks the caller not to perform a default action.

function handler(e) {
    if (iBusy()) {
        e.preventDefault();
    } else {
        // pre remove
    }
}

emitter->add("delete", handler);

// ...

function removeUser(userId) {
    var event = emitter->emit("delete", {id: userId});
    if (event.isDefaultPrevented()) {
        return false;
    }
    // remove user
    return true;
}

isDefaultPrevented()

Checks if preventDefault() has been called.

Note: methods name "prevent default" and "stop propagation" taken from DOM events. Here they are not entirely accurate.