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@ -167,6 +167,9 @@ myEmitter.emit('error', new Error('whoops!')); |
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``` |
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``` |
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## Class: EventEmitter |
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## Class: EventEmitter |
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<!-- YAML |
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added: v0.1.26 |
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--> |
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The `EventEmitter` class is defined and exposed by the `events` module: |
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The `EventEmitter` class is defined and exposed by the `events` module: |
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@ -178,6 +181,9 @@ All EventEmitters emit the event `'newListener'` when new listeners are |
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added and `'removeListener'` when existing listeners are removed. |
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added and `'removeListener'` when existing listeners are removed. |
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### Event: 'newListener' |
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### Event: 'newListener' |
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<!-- YAML |
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added: v0.1.26 |
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--> |
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* `eventName` {String|Symbol} The name of the event being listened for |
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* `eventName` {String|Symbol} The name of the event being listened for |
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* `listener` {Function} The event handler function |
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* `listener` {Function} The event handler function |
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@ -214,6 +220,9 @@ myEmitter.emit('event'); |
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``` |
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``` |
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### Event: 'removeListener' |
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### Event: 'removeListener' |
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<!-- YAML |
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added: v0.9.3 |
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--> |
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* `eventName` {String|Symbol} The event name |
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* `eventName` {String|Symbol} The event name |
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* `listener` {Function} The event handler function |
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* `listener` {Function} The event handler function |
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@ -221,6 +230,10 @@ myEmitter.emit('event'); |
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The `'removeListener'` event is emitted *after* the `listener` is removed. |
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The `'removeListener'` event is emitted *after* the `listener` is removed. |
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### EventEmitter.listenerCount(emitter, eventName) |
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### EventEmitter.listenerCount(emitter, eventName) |
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<!-- YAML |
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added: v0.9.12 |
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deprecated: v4.0.0 |
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--> |
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> Stability: 0 - Deprecated: Use [`emitter.listenerCount()`][] instead. |
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> Stability: 0 - Deprecated: Use [`emitter.listenerCount()`][] instead. |
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@ -236,6 +249,9 @@ console.log(EventEmitter.listenerCount(myEmitter, 'event')); |
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``` |
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``` |
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### EventEmitter.defaultMaxListeners |
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### EventEmitter.defaultMaxListeners |
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<!-- YAML |
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added: v0.11.2 |
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--> |
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By default, a maximum of `10` listeners can be registered for any single |
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By default, a maximum of `10` listeners can be registered for any single |
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event. This limit can be changed for individual `EventEmitter` instances |
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event. This limit can be changed for individual `EventEmitter` instances |
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@ -263,10 +279,16 @@ emitter.once('event', () => { |
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``` |
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``` |
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### emitter.addListener(eventName, listener) |
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### emitter.addListener(eventName, listener) |
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<!-- YAML |
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added: v0.1.26 |
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--> |
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Alias for `emitter.on(eventName, listener)`. |
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Alias for `emitter.on(eventName, listener)`. |
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### emitter.emit(eventName[, arg1][, arg2][, ...]) |
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### emitter.emit(eventName[, arg1][, arg2][, ...]) |
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<!-- YAML |
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added: v0.1.26 |
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--> |
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Synchronously calls each of the listeners registered for the event named |
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Synchronously calls each of the listeners registered for the event named |
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`eventName`, in the order they were registered, passing the supplied arguments |
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`eventName`, in the order they were registered, passing the supplied arguments |
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@ -275,6 +297,9 @@ to each. |
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Returns `true` if the event had listeners, `false` otherwise. |
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Returns `true` if the event had listeners, `false` otherwise. |
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### emitter.eventNames() |
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### emitter.eventNames() |
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<!-- YAML |
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added: v6.0.0 |
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--> |
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Returns an array listing the events for which the emitter has registered |
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Returns an array listing the events for which the emitter has registered |
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listeners. The values in the array will be strings or Symbols. |
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listeners. The values in the array will be strings or Symbols. |
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@ -293,18 +318,27 @@ console.log(myEE.eventNames()); |
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``` |
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``` |
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### emitter.getMaxListeners() |
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### emitter.getMaxListeners() |
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<!-- YAML |
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added: v1.0.0 |
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--> |
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Returns the current max listener value for the `EventEmitter` which is either |
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Returns the current max listener value for the `EventEmitter` which is either |
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set by [`emitter.setMaxListeners(n)`][] or defaults to |
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set by [`emitter.setMaxListeners(n)`][] or defaults to |
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[`EventEmitter.defaultMaxListeners`][]. |
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[`EventEmitter.defaultMaxListeners`][]. |
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### emitter.listenerCount(eventName) |
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### emitter.listenerCount(eventName) |
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<!-- YAML |
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added: v3.2.0 |
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--> |
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* `eventName` {String|Symbol} The name of the event being listened for |
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* `eventName` {String|Symbol} The name of the event being listened for |
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Returns the number of listeners listening to the event named `eventName`. |
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Returns the number of listeners listening to the event named `eventName`. |
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### emitter.listeners(eventName) |
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### emitter.listeners(eventName) |
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<!-- YAML |
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added: v0.1.26 |
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--> |
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Returns a copy of the array of listeners for the event named `eventName`. |
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Returns a copy of the array of listeners for the event named `eventName`. |
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@ -317,6 +351,9 @@ console.log(util.inspect(server.listeners('connection'))); |
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``` |
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``` |
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### emitter.on(eventName, listener) |
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### emitter.on(eventName, listener) |
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<!-- YAML |
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added: v0.1.101 |
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--> |
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* `eventName` {String|Symbol} The name of the event. |
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* `eventName` {String|Symbol} The name of the event. |
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* `listener` {Function} The callback function |
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* `listener` {Function} The callback function |
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@ -350,6 +387,9 @@ myEE.emit('foo'); |
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``` |
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``` |
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### emitter.once(eventName, listener) |
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### emitter.once(eventName, listener) |
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<!-- YAML |
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added: v0.3.0 |
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--> |
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* `eventName` {String|Symbol} The name of the event. |
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* `eventName` {String|Symbol} The name of the event. |
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* `listener` {Function} The callback function |
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* `listener` {Function} The callback function |
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@ -380,6 +420,9 @@ myEE.emit('foo'); |
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``` |
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``` |
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### emitter.prependListener(eventName, listener) |
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### emitter.prependListener(eventName, listener) |
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<!-- YAML |
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added: v6.0.0 |
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--> |
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* `eventName` {String|Symbol} The name of the event. |
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* `eventName` {String|Symbol} The name of the event. |
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* `listener` {Function} The callback function |
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* `listener` {Function} The callback function |
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@ -399,6 +442,9 @@ server.prependListener('connection', (stream) => { |
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Returns a reference to the `EventEmitter`, so that calls can be chained. |
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Returns a reference to the `EventEmitter`, so that calls can be chained. |
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### emitter.prependOnceListener(eventName, listener) |
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### emitter.prependOnceListener(eventName, listener) |
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<!-- YAML |
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added: v6.0.0 |
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--> |
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* `eventName` {String|Symbol} The name of the event. |
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* `eventName` {String|Symbol} The name of the event. |
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* `listener` {Function} The callback function |
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* `listener` {Function} The callback function |
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@ -416,6 +462,9 @@ server.prependOnceListener('connection', (stream) => { |
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Returns a reference to the `EventEmitter`, so that calls can be chained. |
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Returns a reference to the `EventEmitter`, so that calls can be chained. |
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### emitter.removeAllListeners([eventName]) |
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### emitter.removeAllListeners([eventName]) |
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<!-- YAML |
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added: v0.1.26 |
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--> |
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Removes all listeners, or those of the specified `eventName`. |
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Removes all listeners, or those of the specified `eventName`. |
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@ -426,6 +475,9 @@ component or module (e.g. sockets or file streams). |
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Returns a reference to the `EventEmitter`, so that calls can be chained. |
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Returns a reference to the `EventEmitter`, so that calls can be chained. |
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### emitter.removeListener(eventName, listener) |
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### emitter.removeListener(eventName, listener) |
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<!-- YAML |
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added: v0.1.26 |
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--> |
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Removes the specified `listener` from the listener array for the event named |
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Removes the specified `listener` from the listener array for the event named |
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`eventName`. |
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`eventName`. |
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@ -490,6 +542,9 @@ the `emitter.listeners()` method will need to be recreated. |
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Returns a reference to the `EventEmitter`, so that calls can be chained. |
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Returns a reference to the `EventEmitter`, so that calls can be chained. |
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### emitter.setMaxListeners(n) |
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### emitter.setMaxListeners(n) |
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<!-- YAML |
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added: v0.3.5 |
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--> |
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By default EventEmitters will print a warning if more than `10` listeners are |
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By default EventEmitters will print a warning if more than `10` listeners are |
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added for a particular event. This is a useful default that helps finding |
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added for a particular event. This is a useful default that helps finding |
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