وحدة أحداث Node.js
مثال
اجعل مستمعًا لحدث يسمى "صرخة" ، ثم استفزه:
var events = require('events');
var eventEmitter = new
events.EventEmitter();
eventEmitter.on('scream', function() {
console.log('A scream is detected!');
});
eventEmitter.emit('scream');
التعريف والاستخدام
توفر وحدة الأحداث طريقة للعمل مع الأحداث.
في Node.js ، جميع الأحداث هي مثيل لكائن EventEmitter
بناء الجملة
بناء الجملة لتضمين وحدة الأحداث ، وإنشاء EventEmitter في تطبيقك:
var events = require('events');
var eventEmitter = new events.EventEmitter();
خصائص وطرق EventEmitter
| 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 |