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v4.x backport: doc: add added: information for events #8879

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v4.x backport: doc: add added: information for events #8879

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46 changes: 46 additions & 0 deletions doc/api/events.md
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Original file line number Diff line number Diff line change
Expand Up @@ -189,6 +189,9 @@ myEmitter.emit('error', new Error('whoops!'));
```

## Class: EventEmitter
<!-- YAML
added: v0.1.26
-->

The `EventEmitter` class is defined and exposed by the `events` module:

Expand All @@ -200,6 +203,9 @@ All EventEmitters emit the event `'newListener'` when new listeners are
added and `'removeListener'` when a listener is removed.

### Event: 'newListener'
<!-- YAML
added: v0.1.26
-->

* `eventName` {String|Symbol} The name of the event being listened for
* `listener` {Function} The event handler function
Expand Down Expand Up @@ -236,13 +242,20 @@ myEmitter.emit('event');
```

### Event: 'removeListener'
<!-- YAML
added: v0.9.3
-->

* `eventName` {String|Symbol} The event name
* `listener` {Function} The event handler function

The `'removeListener'` event is emitted *after* a listener is removed.

### EventEmitter.listenerCount(emitter, eventName)
<!-- YAML
added: v0.9.12
deprecated: v4.0.0
-->

> Stability: 0 - Deprecated: Use [`emitter.listenerCount()`][] instead.

Expand All @@ -258,6 +271,9 @@ console.log(EventEmitter.listenerCount(myEmitter, 'event'));
```

### EventEmitter.defaultMaxListeners
<!-- YAML
added: v0.11.2
-->

By default, a maximum of `10` listeners can be registered for any single
event. This limit can be changed for individual `EventEmitter` instances
Expand Down Expand Up @@ -285,10 +301,16 @@ emitter.once('event', () => {
```

### emitter.addListener(eventName, listener)
<!-- YAML
added: v0.1.26
-->

Alias for `emitter.on(eventName, listener)`.

### emitter.emit(eventName[, arg1][, arg2][, ...])
<!-- YAML
added: v0.1.26
-->

Synchronously calls each of the listeners registered for the event named
`eventName`, in the order they were registered, passing the supplied arguments
Expand All @@ -297,18 +319,27 @@ to each.
Returns `true` if the event had listeners, `false` otherwise.

### emitter.getMaxListeners()
<!-- YAML
added: v1.0.0
-->

Returns the current max listener value for the `EventEmitter` which is either
set by [`emitter.setMaxListeners(n)`][] or defaults to
[`EventEmitter.defaultMaxListeners`][].

### emitter.listenerCount(eventName)
<!-- YAML
added: v3.2.0
-->

* `eventName` {Value} The name of the event being listened for

Returns the number of listeners listening to the event named `eventName`.

### emitter.listeners(eventName)
<!-- YAML
added: v0.1.26
-->

Returns a copy of the array of listeners for the event named `eventName`.

Expand All @@ -321,6 +352,9 @@ console.log(util.inspect(server.listeners('connection')));
```

### emitter.on(eventName, listener)
<!-- YAML
added: v0.1.101
-->

Adds the `listener` function to the end of the listeners array for the
event named `eventName`. No checks are made to see if the `listener` has
Expand All @@ -337,6 +371,9 @@ server.on('connection', (stream) => {
Returns a reference to the `EventEmitter` so calls can be chained.

### emitter.once(eventName, listener)
<!-- YAML
added: v0.3.0
-->

Adds a **one time** `listener` function for the event named `eventName`. The
next time `eventName` is triggered, this listener is removed and then invoked.
Expand All @@ -350,6 +387,9 @@ server.once('connection', (stream) => {
Returns a reference to the `EventEmitter` so calls can be chained.

### emitter.removeAllListeners([eventName])
<!-- YAML
added: v0.1.26
-->

Removes all listeners, or those of the specified `eventName`.

Expand All @@ -360,6 +400,9 @@ component or module (e.g. sockets or file streams).
Returns a reference to the `EventEmitter` so calls can be chained.

### emitter.removeListener(eventName, listener)
<!-- YAML
added: v0.1.26
-->

Removes the specified `listener` from the listener array for the event named
`eventName`.
Expand Down Expand Up @@ -424,6 +467,9 @@ the `emitter.listeners()` method will need to be recreated.
Returns a reference to the `EventEmitter` so calls can be chained.

### emitter.setMaxListeners(n)
<!-- YAML
added: v0.3.5
-->

By default EventEmitters will print a warning if more than `10` listeners are
added for a particular event. This is a useful default that helps finding
Expand Down