Node.js - Ereignismodul
Beispiel
Erstellen Sie einen Ereignis-Listener für ein Ereignis namens "scream", und provozieren Sie dann das Ereignis:
var events = require('events');
var eventEmitter = new
events.EventEmitter();
eventEmitter.on('scream', function() {
console.log('A scream is detected!');
});
eventEmitter.emit('scream');
Definition und Verwendung
Das Modul „Ereignisse“ bietet eine Möglichkeit, mit Ereignissen zu arbeiten.
In Node.js sind alle Ereignisse eine Instanz des EventEmitter-Objekts
Syntax
Die Syntax zum Einbinden des Events-Moduls und zum Erstellen eines EventEmitters in Ihrer Anwendung:
var events = require('events');
var eventEmitter = new events.EventEmitter();
EventEmitter-Eigenschaften und -Methoden
| 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 |