IoT.js-API-Events.md

The application programming model of IoT.js is based on event-driven programming. Thus many objects in IoT.js emit events. events.EventEmitter plays a role as base class for such objects.

Class: EventEmitter

User application would not directly create an instance of EventEmitter since EventEmitter is an abstract trait which defines its behavior and grants to sub-classes.

Methods

emitter.addListener(event, listener)

emitter.on(event, listener)

• event: String
• listener: Function([args..])
• Returns emitter

Adds listener to the end of list of event listeners for event.

emitter.emit(event[, arg1[, arg2[...]]])

• event: String
• Returns Boolean

Invokes each of listener with supplied arguments.

Returns true if there were listeners, false otherwise.

emitter.once(event, listener)

• event: String
• listener: Function([args..])
• Returns emitter

Adds listener for one time listener for event.

The listener will be invoked at the next event and removed.

emitter.removeListener(event, listener)

• event: String
• listener: Function([args..])
• Returns emitter

Removes listener from the list of event listeners.

If you add the same listener multiple times, this removes only one instance of them.

emitter.removeAllListener([event])

• event: String
• Returns emitter

Removes all listeners.

If event was specified, it only removes listeners for that event.