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podium

podium

Node (semi) compatible event emitter with extra features.

podium is an event emitter with support for tags, filters, channels, event update cloning, arguments spreading, and other features useful when building large scale applications. While node's native EventEmitter is strictly focused on maximum performance, it lacks many features that do not belong in the core implementation. podium is not restricted by node's performance requirement as it is designed for application layer needs where it's overhead is largely insignificant as implementing these features will have similar cost on top of the native emitter.

Build Status

Lead Maintainer - Eran Hammer

new Podium(events)

This creates a new event emitter.

const Podium = require('podium');
const podiumObject = new Podium(); // new emitter 
 
const podiumObject2 = new Podium('event1');// creates new event and calls registerEvent() 

podium.registerEvent(events)

Registers an event event1 to emitter.

podiumObject.registerEvent('event1');
 
//with optional parameters 
podiumObject.registerEvent({
        name: 'event1',
        shared: true
 });

podium.on(criteria, listener)

Subscribe a handler to an event. Handler can be seen a function which will be called when the event occurs.

podiumObject.registerEvent('event1');
 
podiumObject.on('event1',function(update){ // Way 1 
    console.log('inside autonomous listener without name! data:', update);
});
 
const listener1 = function() { // normal function object 
    console.log('listener1 called');
}
podiumObject.on('event1',listener1); // Way 2 

podium.addListener(criteria, listener)

Same as podium.on().

podiumObject.addListener('event1',listener1);

podium.once(criteria, listener)

Same as calling podium.on() with the count option set to 1. Whenever we call emit(), listener1 will get fired but also get removed, so that it won't get fired on call to emit().

podiumObject.once('event1',listener1);

podium.emit(criteria, data, [callback])

Emits an event update to all the subscribed listeners.

podiumObject.emit('event1','here we can send any data to listeners.');

podium.removeListener(name, listener)

Removes all listeners subscribed to a given event name matching the provided listener method.

podiumObject.removeListener('event1',listener1);

podium.removeAllListeners(name)

Removes all listeners subscribed to a given event name.

podiumObject.removeAllListeners('event1');

podium.hasListeners(name)

Returns whether an event has any listeners subscribed.

if(podiumObject.hasListeners('event1')){
    console.log('this event has some listeners left');
}
else{
    console.log('this event has no listeners');
}
 

podium.registerPodium(podiums)

Registers a podium object(emitter) to another podium object(source). Whenever any event gets registered on emitterObject it gets registered on sourceObject as well. But reverse is not true.

const source1Object = new Podium('test');
const source2Object = new Podium('test');
 
const emitterObject = new Podium(source1Object);
emitterObject.registerPodium(source2Object);
 
const listener1 = function() { // normal function 
    console.log('listener1 called');
}
const listener2 = function() { // another normal function 
    console.log('listener1 called');
}
emitterObject.on('test',listener1); // listener1 gets registered on emitterObject, source1Object,source2Object events 
source1Object.on('test',listener2); // listener2 gets registered on source1Object events only 
 
source1Object.emit('test', 1); // runs all registered events 
emitterObject.emit('test', 2);

API

The full API is available in the API documentation.