Node.js Events Module
Example
Make an event listener for an event called "scream", then provoke the event:
var events = require('events');
var eventEmitter = new
events.EventEmitter();
eventEmitter.on('scream', function() {
console.log('A scream is detected!');
});
eventEmitter.emit('scream');
Run example »
Defintion and Usage
The Events module provides a way of working with events.
In Node.js, all events are an instance of the EventEmitter object
Syntax
The syntax for including the Events module, and creating an EventEmitter in your application:
var events = require('events');
var eventEmitter = new events.EventEmitter();
EventEmitter Properties and Methods
| Method | Description |
|---|---|
| addListener() | Adds the specified listener |
| defaultMaxListeners | Sets the maximum number of listeners allowed for one event. Default is 10 |
| emit() | Call all the listeners registered with the specified name |
| eventNames() | Returns an array containing all registered events |
| getMaxListeners() | Returns the maximum number of listeners allowed for one event |
| listenerCount() | Returns the number of listeners with the specified name |
| listeners() | Returns an array of listeners with the specified name |
| on() | Adds the specified listener |
| once() | Adds the specified listener once. When the specified listener has been executed, the listener is removed |
| prependListener() | Adds the specified listener as the first event with the specified name |
| prependOnceListener() | Adds the specified listener as the first event with the specified name, once. When the specified listener has been executed, the listener is removed |
| removeAllListeners() | Removes all listeners with the specified name, or ALL listeners if no name is specified |
| removeListener() | Removes the specified listener with the specified name |
| setMaxListeners() | Sets the maximum number of listeners allowed for one event. Default is 10 |
