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doc: add example about emitter.emit in events documentation #28374

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46ae972
doc: add example about emitter.emit in events documentation
felipedc09 Jun 21, 2019
de07417
modify emitter.emit example to simplify the use
felipedc09 Jun 26, 2019
5ab4be1
fix lint exceptions
felipedc09 Jun 30, 2019
5c1bb28
formating prints
felipedc09 Jun 30, 2019
924c547
fix spaces to run lint
felipedc09 Jul 1, 2019
2524a00
Update events.md
Trott Jul 30, 2019
566f830
Update events.md
Trott Jul 30, 2019
489dcde
Update events.md
Trott Jul 30, 2019
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37 changes: 37 additions & 0 deletions doc/api/events.md
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Original file line number Diff line number Diff line change
Expand Up @@ -307,6 +307,43 @@ to each.

Returns `true` if the event had listeners, `false` otherwise.


```js
const EventEmitter = require('events');
class MyEmitter extends EventEmitter { }

const myEmitter = new MyEmitter();

// First listener
myEmitter.on('event', function firstListener() {
console.log('Helloooo! first listener');
});
// Second listener
myEmitter.on('event', function secondListener(a, b) {
console.log(`an event with parameters ${a},${b} occurred in second listener`);
});
// Third listener
myEmitter.on('event', function thirdListener(...arrgParms) {
let params = '';
arrgParms.forEach((param) => {
params += `-${param}`;
}
);
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@BridgeAR BridgeAR Jul 4, 2019

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Please move this closing bracket to the line above. It's otherwise a bit confusing.

It could also be simplified by using join:

  const parameters = args.join(', ');

console.log(`an event with parameters ${params} occurred in third listener`);
});

console.log(myEmitter.listeners('event'));
myEmitter.emit('event', 1, 2, 3, 4, 5);

// Prints:
// [ [Function: firstListener],
// [Function: secondListener],
// [Function: thirdListener] ]
// Helloooo! first listener
// an event with parameters 1 - 2, occurred in second listener
// an event with parameters -1-2-3-4-5 occurred in third listener
```

### emitter.eventNames()
<!-- YAML
added: v6.0.0
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