node.js: emitter.prependListener(eventName, listener)

emitter.prependListener(eventName, listener)

Prepend a listener function to the beginning of the array for the event named eventName.

HelloWorld.js

var EventEmitter = require('events').EventEmitter;

var emitter = new EventEmitter();

emitter.on('sayHello', () => {
 console.log('Hello Visitor');
});

emitter.emit('sayHello');

console.log('Prepended another listener function to the event "sayHello"');

emitter.prependListener('sayHello', (stream) => {
 console.log('Good Morning!!!!!!!');
});

emitter.emit('sayHello');

Output

Hello Visitor

Prepended another listener function to the event "sayHello"

Good Morning!!!!!!!

Hello Visitor

Note

a.   This method returns a reference to the EventEmitter, so that calls can be chained.

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