---
title: "EventEmitter | JavaScript maps SDK"
description: "Documentation for MapTiler SDK"
---

> For AI agents: a documentation index is available at [/llms.txt](https://docs.maptiler.com/llms.txt). Markdown versions of all pages are available by appending .md to any URL.

# Interface EventEmitter<T>

interface EventEmitter<[T](#t) extends [EventMap](https://docs.maptiler.com/sdk-js/api-reference/types/Externals.EventMap/)<[T](#t)\> \= any\> {  
    ["\[captureRejectionSymbol\]"](#capturerejectionsymbol-1)?(  
        error: Error,  
        event: string | symbol,  
        ...args: any\[\],  
    ): void;  
    [addListener](#addlistener-1)<[E](#addlistenere) extends string | symbol\>(  
        eventName: [IfEventMap](https://docs.maptiler.com/sdk-js/api-reference/types/Externals.IfEventMap/)<  
            [T](#t),  
            (keyof EventEmitterEventMap)  
            | (keyof T & (string | symbol))  
            | [E](https://docs.maptiler.com/sdk-js/api-reference/classes/SdkConfig/#addlistenere),  
        \>,  
        listener: [IfEventMap](https://docs.maptiler.com/sdk-js/api-reference/types/Externals.IfEventMap/)<  
            [T](#t),  
            (  
                ...args: [E](https://docs.maptiler.com/sdk-js/api-reference/classes/SdkConfig/#addlistenere) extends keyof [T](#t)  
                    ? [T](#t)\[[E](https://docs.maptiler.com/sdk-js/api-reference/classes/SdkConfig/#addlistenere)\]  
                    : [E](https://docs.maptiler.com/sdk-js/api-reference/classes/SdkConfig/#addlistenere) extends keyof [EventEmitterEventMap](https://docs.maptiler.com/sdk-js/api-reference/interfaces/Externals.EventEmitter.EventEmitterEventMap/)  
                        ? [EventEmitterEventMap](https://docs.maptiler.com/sdk-js/api-reference/interfaces/Externals.EventEmitter.EventEmitterEventMap/)\[[E](https://docs.maptiler.com/sdk-js/api-reference/classes/SdkConfig/#addlistenere)\]  
                        : any\[\],  
            ) \=> void,  
        \>,  
    ): this;  
    [emit](#emit-1)<[E](#emite) extends string | symbol\>(  
        eventName: [IfEventMap](https://docs.maptiler.com/sdk-js/api-reference/types/Externals.IfEventMap/)<  
            [T](#t),  
            (keyof EventEmitterEventMap)  
            | (keyof T & (string | symbol))  
            | [E](https://docs.maptiler.com/sdk-js/api-reference/classes/SdkConfig/#emite),  
        \>,  
        ...args: [IfEventMap](https://docs.maptiler.com/sdk-js/api-reference/types/Externals.IfEventMap/)<  
            [T](#t),  
            [E](https://docs.maptiler.com/sdk-js/api-reference/classes/SdkConfig/#emite) extends keyof [T](#t)  
                ? [T](#t)\[[E](https://docs.maptiler.com/sdk-js/api-reference/classes/SdkConfig/#emite)\]  
                : [E](https://docs.maptiler.com/sdk-js/api-reference/classes/SdkConfig/#emite) extends keyof [EventEmitterEventMap](https://docs.maptiler.com/sdk-js/api-reference/interfaces/Externals.EventEmitter.EventEmitterEventMap/) ? [EventEmitterEventMap](https://docs.maptiler.com/sdk-js/api-reference/interfaces/Externals.EventEmitter.EventEmitterEventMap/)\[[E](https://docs.maptiler.com/sdk-js/api-reference/classes/SdkConfig/#emite)\] : any\[\],  
        \>,  
    ): boolean;  
    [eventNames](#eventnames-1)(): (string | symbol)\[\];  
    [getMaxListeners](#getmaxlisteners-1)(): number;  
    [listenerCount](#listenercount-1)<[E](#listenercounte) extends string | symbol\>(  
        eventName: [IfEventMap](https://docs.maptiler.com/sdk-js/api-reference/types/Externals.IfEventMap/)<  
            [T](#t),  
            (keyof EventEmitterEventMap)  
            | (keyof T & (string | symbol))  
            | [E](https://docs.maptiler.com/sdk-js/api-reference/classes/SdkConfig/#listenercounte),  
        \>,  
        listener?: [IfEventMap](https://docs.maptiler.com/sdk-js/api-reference/types/Externals.IfEventMap/)<  
            [T](#t),  
            (  
                ...args: [E](https://docs.maptiler.com/sdk-js/api-reference/classes/SdkConfig/#listenercounte) extends keyof [T](#t)  
                    ? [T](#t)\[[E](https://docs.maptiler.com/sdk-js/api-reference/classes/SdkConfig/#listenercounte)\]  
                    : [E](https://docs.maptiler.com/sdk-js/api-reference/classes/SdkConfig/#listenercounte) extends keyof [EventEmitterEventMap](https://docs.maptiler.com/sdk-js/api-reference/interfaces/Externals.EventEmitter.EventEmitterEventMap/)  
                        ? [EventEmitterEventMap](https://docs.maptiler.com/sdk-js/api-reference/interfaces/Externals.EventEmitter.EventEmitterEventMap/)\[[E](https://docs.maptiler.com/sdk-js/api-reference/classes/SdkConfig/#listenercounte)\]  
                        : any\[\],  
            ) \=> void,  
            (...args: any\[\]) \=> void,  
        \>,  
    ): number;  
    [listeners](#listeners-1)<[E](#listenerse) extends string | symbol\>(  
        eventName: [IfEventMap](https://docs.maptiler.com/sdk-js/api-reference/types/Externals.IfEventMap/)<  
            [T](#t),  
            (keyof EventEmitterEventMap)  
            | (keyof T & (string | symbol))  
            | [E](https://docs.maptiler.com/sdk-js/api-reference/classes/SdkConfig/#listenerse),  
        \>,  
    ): [IfEventMap](https://docs.maptiler.com/sdk-js/api-reference/types/Externals.IfEventMap/)<  
        [T](#t),  
        (  
            ...args: [E](https://docs.maptiler.com/sdk-js/api-reference/classes/SdkConfig/#listenerse) extends keyof [T](#t)  
                ? [T](#t)\[[E](https://docs.maptiler.com/sdk-js/api-reference/classes/SdkConfig/#listenerse)\]  
                : [E](https://docs.maptiler.com/sdk-js/api-reference/classes/SdkConfig/#listenerse) extends keyof [EventEmitterEventMap](https://docs.maptiler.com/sdk-js/api-reference/interfaces/Externals.EventEmitter.EventEmitterEventMap/) ? [EventEmitterEventMap](https://docs.maptiler.com/sdk-js/api-reference/interfaces/Externals.EventEmitter.EventEmitterEventMap/)\[[E](https://docs.maptiler.com/sdk-js/api-reference/classes/SdkConfig/#listenerse)\] : any\[\],  
        ) \=> void,  
        (...args: any\[\]) \=> void,  
    \>\[\];  
    [off](#off-1)<[E](#offe) extends string | symbol\>(  
        eventName: [IfEventMap](https://docs.maptiler.com/sdk-js/api-reference/types/Externals.IfEventMap/)<  
            [T](#t),  
            (keyof EventEmitterEventMap)  
            | (keyof T & (string | symbol))  
            | [E](https://docs.maptiler.com/sdk-js/api-reference/classes/SdkConfig/#offe),  
        \>,  
        listener: [IfEventMap](https://docs.maptiler.com/sdk-js/api-reference/types/Externals.IfEventMap/)<  
            [T](#t),  
            (  
                ...args: [E](https://docs.maptiler.com/sdk-js/api-reference/classes/SdkConfig/#offe) extends keyof [T](#t)  
                    ? [T](#t)\[[E](https://docs.maptiler.com/sdk-js/api-reference/classes/SdkConfig/#offe)\]  
                    : [E](https://docs.maptiler.com/sdk-js/api-reference/classes/SdkConfig/#offe) extends keyof [EventEmitterEventMap](https://docs.maptiler.com/sdk-js/api-reference/interfaces/Externals.EventEmitter.EventEmitterEventMap/)  
                        ? [EventEmitterEventMap](https://docs.maptiler.com/sdk-js/api-reference/interfaces/Externals.EventEmitter.EventEmitterEventMap/)\[[E](https://docs.maptiler.com/sdk-js/api-reference/classes/SdkConfig/#offe)\]  
                        : any\[\],  
            ) \=> void,  
        \>,  
    ): this;  
    [on](#on-1)<[E](#one) extends string | symbol\>(  
        eventName: [IfEventMap](https://docs.maptiler.com/sdk-js/api-reference/types/Externals.IfEventMap/)<  
            [T](#t),  
            (keyof EventEmitterEventMap)  
            | (keyof T & (string | symbol))  
            | [E](https://docs.maptiler.com/sdk-js/api-reference/classes/SdkConfig/#one),  
        \>,  
        listener: [IfEventMap](https://docs.maptiler.com/sdk-js/api-reference/types/Externals.IfEventMap/)<  
            [T](#t),  
            (  
                ...args: [E](https://docs.maptiler.com/sdk-js/api-reference/classes/SdkConfig/#one) extends keyof [T](#t)  
                    ? [T](#t)\[[E](https://docs.maptiler.com/sdk-js/api-reference/classes/SdkConfig/#one)\]  
                    : [E](https://docs.maptiler.com/sdk-js/api-reference/classes/SdkConfig/#one) extends keyof [EventEmitterEventMap](https://docs.maptiler.com/sdk-js/api-reference/interfaces/Externals.EventEmitter.EventEmitterEventMap/)  
                        ? [EventEmitterEventMap](https://docs.maptiler.com/sdk-js/api-reference/interfaces/Externals.EventEmitter.EventEmitterEventMap/)\[[E](https://docs.maptiler.com/sdk-js/api-reference/classes/SdkConfig/#one)\]  
                        : any\[\],  
            ) \=> void,  
        \>,  
    ): this;  
    [once](#once-1)<[E](#oncee) extends string | symbol\>(  
        eventName: [IfEventMap](https://docs.maptiler.com/sdk-js/api-reference/types/Externals.IfEventMap/)<  
            [T](#t),  
            (keyof EventEmitterEventMap)  
            | (keyof T & (string | symbol))  
            | [E](https://docs.maptiler.com/sdk-js/api-reference/classes/SdkConfig/#oncee),  
        \>,  
        listener: [IfEventMap](https://docs.maptiler.com/sdk-js/api-reference/types/Externals.IfEventMap/)<  
            [T](#t),  
            (  
                ...args: [E](https://docs.maptiler.com/sdk-js/api-reference/classes/SdkConfig/#oncee) extends keyof [T](#t)  
                    ? [T](#t)\[[E](https://docs.maptiler.com/sdk-js/api-reference/classes/SdkConfig/#oncee)\]  
                    : [E](https://docs.maptiler.com/sdk-js/api-reference/classes/SdkConfig/#oncee) extends keyof [EventEmitterEventMap](https://docs.maptiler.com/sdk-js/api-reference/interfaces/Externals.EventEmitter.EventEmitterEventMap/)  
                        ? [EventEmitterEventMap](https://docs.maptiler.com/sdk-js/api-reference/interfaces/Externals.EventEmitter.EventEmitterEventMap/)\[[E](https://docs.maptiler.com/sdk-js/api-reference/classes/SdkConfig/#oncee)\]  
                        : any\[\],  
            ) \=> void,  
        \>,  
    ): this;  
    [prependListener](#prependlistener-1)<[E](#prependlistenere) extends string | symbol\>(  
        eventName: [IfEventMap](https://docs.maptiler.com/sdk-js/api-reference/types/Externals.IfEventMap/)<  
            [T](#t),  
            (keyof EventEmitterEventMap)  
            | (keyof T & (string | symbol))  
            | [E](https://docs.maptiler.com/sdk-js/api-reference/classes/SdkConfig/#prependlistenere),  
        \>,  
        listener: [IfEventMap](https://docs.maptiler.com/sdk-js/api-reference/types/Externals.IfEventMap/)<  
            [T](#t),  
            (  
                ...args: [E](https://docs.maptiler.com/sdk-js/api-reference/classes/SdkConfig/#prependlistenere) extends keyof [T](#t)  
                    ? [T](#t)\[[E](https://docs.maptiler.com/sdk-js/api-reference/classes/SdkConfig/#prependlistenere)\]  
                    : [E](https://docs.maptiler.com/sdk-js/api-reference/classes/SdkConfig/#prependlistenere) extends keyof [EventEmitterEventMap](https://docs.maptiler.com/sdk-js/api-reference/interfaces/Externals.EventEmitter.EventEmitterEventMap/)  
                        ? [EventEmitterEventMap](https://docs.maptiler.com/sdk-js/api-reference/interfaces/Externals.EventEmitter.EventEmitterEventMap/)\[[E](https://docs.maptiler.com/sdk-js/api-reference/classes/SdkConfig/#prependlistenere)\]  
                        : any\[\],  
            ) \=> void,  
        \>,  
    ): this;  
    [prependOnceListener](#prependoncelistener-1)<[E](#prependoncelistenere) extends string | symbol\>(  
        eventName: [IfEventMap](https://docs.maptiler.com/sdk-js/api-reference/types/Externals.IfEventMap/)<  
            [T](#t),  
            (keyof EventEmitterEventMap)  
            | (keyof T & (string | symbol))  
            | [E](https://docs.maptiler.com/sdk-js/api-reference/classes/SdkConfig/#prependoncelistenere),  
        \>,  
        listener: [IfEventMap](https://docs.maptiler.com/sdk-js/api-reference/types/Externals.IfEventMap/)<  
            [T](#t),  
            (  
                ...args: [E](https://docs.maptiler.com/sdk-js/api-reference/classes/SdkConfig/#prependoncelistenere) extends keyof [T](#t)  
                    ? [T](#t)\[[E](https://docs.maptiler.com/sdk-js/api-reference/classes/SdkConfig/#prependoncelistenere)\]  
                    : [E](https://docs.maptiler.com/sdk-js/api-reference/classes/SdkConfig/#prependoncelistenere) extends keyof [EventEmitterEventMap](https://docs.maptiler.com/sdk-js/api-reference/interfaces/Externals.EventEmitter.EventEmitterEventMap/)  
                        ? [EventEmitterEventMap](https://docs.maptiler.com/sdk-js/api-reference/interfaces/Externals.EventEmitter.EventEmitterEventMap/)\[[E](https://docs.maptiler.com/sdk-js/api-reference/classes/SdkConfig/#prependoncelistenere)\]  
                        : any\[\],  
            ) \=> void,  
        \>,  
    ): this;  
    [rawListeners](#rawlisteners-1)<[E](#rawlistenerse) extends string | symbol\>(  
        eventName: [IfEventMap](https://docs.maptiler.com/sdk-js/api-reference/types/Externals.IfEventMap/)<  
            [T](#t),  
            (keyof EventEmitterEventMap)  
            | (keyof T & (string | symbol))  
            | [E](https://docs.maptiler.com/sdk-js/api-reference/classes/SdkConfig/#rawlistenerse),  
        \>,  
    ): [IfEventMap](https://docs.maptiler.com/sdk-js/api-reference/types/Externals.IfEventMap/)<  
        [T](#t),  
        (  
            ...args: [E](https://docs.maptiler.com/sdk-js/api-reference/classes/SdkConfig/#rawlistenerse) extends keyof [T](#t)  
                ? [T](#t)\[[E](https://docs.maptiler.com/sdk-js/api-reference/classes/SdkConfig/#rawlistenerse)\]  
                : [E](https://docs.maptiler.com/sdk-js/api-reference/classes/SdkConfig/#rawlistenerse) extends keyof [EventEmitterEventMap](https://docs.maptiler.com/sdk-js/api-reference/interfaces/Externals.EventEmitter.EventEmitterEventMap/) ? [EventEmitterEventMap](https://docs.maptiler.com/sdk-js/api-reference/interfaces/Externals.EventEmitter.EventEmitterEventMap/)\[[E](https://docs.maptiler.com/sdk-js/api-reference/classes/SdkConfig/#rawlistenerse)\] : any\[\],  
        ) \=> void,  
        (...args: any\[\]) \=> void,  
    \>\[\];  
    [removeAllListeners](#removealllisteners-1)<[E](#removealllistenerse) extends string | symbol\>(  
        eventName?: [IfEventMap](https://docs.maptiler.com/sdk-js/api-reference/types/Externals.IfEventMap/)<  
            [T](#t),  
            (keyof EventEmitterEventMap)  
            | (keyof T & (string | symbol))  
            | [E](https://docs.maptiler.com/sdk-js/api-reference/classes/SdkConfig/#removealllistenerse),  
            string | symbol,  
        \>,  
    ): this;  
    [removeListener](#removelistener-1)<[E](#removelistenere) extends string | symbol\>(  
        eventName: [IfEventMap](https://docs.maptiler.com/sdk-js/api-reference/types/Externals.IfEventMap/)<  
            [T](#t),  
            (keyof EventEmitterEventMap)  
            | (keyof T & (string | symbol))  
            | [E](https://docs.maptiler.com/sdk-js/api-reference/classes/SdkConfig/#removelistenere),  
        \>,  
        listener: [IfEventMap](https://docs.maptiler.com/sdk-js/api-reference/types/Externals.IfEventMap/)<  
            [T](#t),  
            (  
                ...args: [E](https://docs.maptiler.com/sdk-js/api-reference/classes/SdkConfig/#removelistenere) extends keyof [T](#t)  
                    ? [T](#t)\[[E](https://docs.maptiler.com/sdk-js/api-reference/classes/SdkConfig/#removelistenere)\]  
                    : [E](https://docs.maptiler.com/sdk-js/api-reference/classes/SdkConfig/#removelistenere) extends keyof [EventEmitterEventMap](https://docs.maptiler.com/sdk-js/api-reference/interfaces/Externals.EventEmitter.EventEmitterEventMap/)  
                        ? [EventEmitterEventMap](https://docs.maptiler.com/sdk-js/api-reference/interfaces/Externals.EventEmitter.EventEmitterEventMap/)\[[E](https://docs.maptiler.com/sdk-js/api-reference/classes/SdkConfig/#removelistenere)\]  
                        : any\[\],  
            ) \=> void,  
        \>,  
    ): this;  
    [setMaxListeners](#setmaxlisteners-1)(n: number): this;  
}

#### Type Parameters

-   T extends [EventMap](https://docs.maptiler.com/sdk-js/api-reference/types/Externals.EventMap/)<[T](#t)\> = any

#### Hierarchy ([View Summary](https://docs.maptiler.com/sdk-js/api-reference/hierarchy/#Externals.EventEmitter))

-   EventEmitter
    -   [EventEmitter](https://docs.maptiler.com/sdk-js/api-reference/classes/Externals.EventEmitter/)

##### Index

### Methods[](#methods)

[\[captureRejectionSymbol\]?](#capturerejectionsymbol) [addListener](#addlistener) [emit](#emit) [eventNames](#eventnames) [getMaxListeners](#getmaxlisteners) [listenerCount](#listenercount) [listeners](#listeners) [off](#off) [on](#on) [once](#once) [prependListener](#prependlistener) [prependOnceListener](#prependoncelistener) [rawListeners](#rawlisteners) [removeAllListeners](#removealllisteners) [removeListener](#removelistener) [setMaxListeners](#setmaxlisteners)

## Methods[](#methods-1)

### `Optional`\[captureRejectionSymbol\][](#capturerejectionsymbol)

-   "\[captureRejectionSymbol\]"?(  
        error: Error,  
        event: string | symbol,  
        ...args: any\[\],  
    ): void[](#capturerejectionsymbol-1)
    
    The `Symbol.for('nodejs.rejection')` method is called in case a promise rejection happens when emitting an event and `captureRejections` is enabled on the emitter. It is possible to use `events.captureRejectionSymbol` in place of `Symbol.for('nodejs.rejection')`.
    
    ```typescript
    import { EventEmitter, captureRejectionSymbol } from 'node:events';
    
    class MyClass extends EventEmitter {
      constructor() {
        super({ captureRejections: true });
      }
    
      [captureRejectionSymbol](err, event, ...args) {
        console.log('rejection happened for', event, 'with', err, ...args);
        this.destroy(err);
      }
    
      destroy(err) {
        // Tear the resource down here.
      }
    }
    ```
    
    #### Parameters
    
    -   error: Error
    -   event: string | symbol
    -   ...args: any\[\]
    
    #### Returns void
    
    #### Since[](#since)
    
    v13.4.0, v12.16.0
    

### addListener[](#addlistener)

-   addListener<[E](#addlistenere) extends string | symbol\>(  
        eventName: [IfEventMap](https://docs.maptiler.com/sdk-js/api-reference/types/Externals.IfEventMap/)<  
            [T](#t),  
            (keyof EventEmitterEventMap)  
            | (keyof T & (string | symbol))  
            | [E](https://docs.maptiler.com/sdk-js/api-reference/classes/SdkConfig/#addlistenere),  
        \>,  
        listener: [IfEventMap](https://docs.maptiler.com/sdk-js/api-reference/types/Externals.IfEventMap/)<  
            [T](#t),  
            (  
                ...args: [E](https://docs.maptiler.com/sdk-js/api-reference/classes/SdkConfig/#addlistenere) extends keyof [T](#t)  
                    ? [T](#t)\[[E](https://docs.maptiler.com/sdk-js/api-reference/classes/SdkConfig/#addlistenere)\]  
                    : [E](https://docs.maptiler.com/sdk-js/api-reference/classes/SdkConfig/#addlistenere) extends keyof [EventEmitterEventMap](https://docs.maptiler.com/sdk-js/api-reference/interfaces/Externals.EventEmitter.EventEmitterEventMap/) ? [EventEmitterEventMap](https://docs.maptiler.com/sdk-js/api-reference/interfaces/Externals.EventEmitter.EventEmitterEventMap/)\[[E](https://docs.maptiler.com/sdk-js/api-reference/classes/SdkConfig/#addlistenere)\] : any\[\],  
            ) \=> void,  
        \>,  
    ): this[](#addlistener-1)
    
    Alias for `emitter.on(eventName, listener)`.
    
    #### Type Parameters
    
    -   E extends string | symbol
    
    #### Parameters
    
    -   eventName: [IfEventMap](https://docs.maptiler.com/sdk-js/api-reference/types/Externals.IfEventMap/)<[T](#t), (keyof EventEmitterEventMap) | (keyof T & (string | symbol)) | [E](https://docs.maptiler.com/sdk-js/api-reference/classes/SdkConfig/#addlistenere)\>
    -   listener: [IfEventMap](https://docs.maptiler.com/sdk-js/api-reference/types/Externals.IfEventMap/)<  
            [T](#t),  
            (  
                ...args: [E](https://docs.maptiler.com/sdk-js/api-reference/classes/SdkConfig/#addlistenere) extends keyof [T](#t)  
                    ? [T](#t)\[[E](https://docs.maptiler.com/sdk-js/api-reference/classes/SdkConfig/#addlistenere)\]  
                    : [E](https://docs.maptiler.com/sdk-js/api-reference/classes/SdkConfig/#addlistenere) extends keyof [EventEmitterEventMap](https://docs.maptiler.com/sdk-js/api-reference/interfaces/Externals.EventEmitter.EventEmitterEventMap/) ? [EventEmitterEventMap](https://docs.maptiler.com/sdk-js/api-reference/interfaces/Externals.EventEmitter.EventEmitterEventMap/)\[[E](https://docs.maptiler.com/sdk-js/api-reference/classes/SdkConfig/#addlistenere)\] : any\[\],  
            ) \=> void,  
        \>
    
    #### Returns this
    
    #### Since[](#since-1)
    
    v0.1.26
    

### emit[](#emit)

-   emit<[E](#emite) extends string | symbol\>(  
        eventName: [IfEventMap](https://docs.maptiler.com/sdk-js/api-reference/types/Externals.IfEventMap/)<  
            [T](#t),  
            (keyof EventEmitterEventMap)  
            | (keyof T & (string | symbol))  
            | [E](https://docs.maptiler.com/sdk-js/api-reference/classes/SdkConfig/#emite),  
        \>,  
        ...args: [IfEventMap](https://docs.maptiler.com/sdk-js/api-reference/types/Externals.IfEventMap/)<  
            [T](#t),  
            [E](https://docs.maptiler.com/sdk-js/api-reference/classes/SdkConfig/#emite) extends keyof [T](#t)  
                ? [T](#t)\[[E](https://docs.maptiler.com/sdk-js/api-reference/classes/SdkConfig/#emite)\]  
                : [E](https://docs.maptiler.com/sdk-js/api-reference/classes/SdkConfig/#emite) extends keyof [EventEmitterEventMap](https://docs.maptiler.com/sdk-js/api-reference/interfaces/Externals.EventEmitter.EventEmitterEventMap/) ? [EventEmitterEventMap](https://docs.maptiler.com/sdk-js/api-reference/interfaces/Externals.EventEmitter.EventEmitterEventMap/)\[[E](https://docs.maptiler.com/sdk-js/api-reference/classes/SdkConfig/#emite)\] : any\[\],  
        \>,  
    ): boolean[](#emit-1)
    
    Synchronously calls each of the listeners registered for the event named `eventName`, in the order they were registered, passing the supplied arguments to each.
    
    Returns `true` if the event had listeners, `false` otherwise.
    
    ```typescript
    import { EventEmitter } from 'node:events';
    const myEmitter = new EventEmitter();
    
    // First listener
    myEmitter.on('event', function firstListener() {
      console.log('Helloooo! first listener');
    });
    // Second listener
    myEmitter.on('event', function secondListener(arg1, arg2) {
      console.log(`event with parameters ${arg1}, ${arg2} in second listener`);
    });
    // Third listener
    myEmitter.on('event', function thirdListener(...args) {
      const parameters = args.join(', ');
      console.log(`event with parameters ${parameters} 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
    // event with parameters 1, 2 in second listener
    // event with parameters 1, 2, 3, 4, 5 in third listener
    ```
    
    #### Type Parameters
    
    -   E extends string | symbol
    
    #### Parameters
    
    -   eventName: [IfEventMap](https://docs.maptiler.com/sdk-js/api-reference/types/Externals.IfEventMap/)<[T](#t), (keyof EventEmitterEventMap) | (keyof T & (string | symbol)) | [E](https://docs.maptiler.com/sdk-js/api-reference/classes/SdkConfig/#emite)\>
    -   ...args: [IfEventMap](https://docs.maptiler.com/sdk-js/api-reference/types/Externals.IfEventMap/)<  
            [T](#t),  
            [E](https://docs.maptiler.com/sdk-js/api-reference/classes/SdkConfig/#emite) extends keyof [T](#t)  
                ? [T](#t)\[[E](https://docs.maptiler.com/sdk-js/api-reference/classes/SdkConfig/#emite)\]  
                : [E](https://docs.maptiler.com/sdk-js/api-reference/classes/SdkConfig/#emite) extends keyof [EventEmitterEventMap](https://docs.maptiler.com/sdk-js/api-reference/interfaces/Externals.EventEmitter.EventEmitterEventMap/) ? [EventEmitterEventMap](https://docs.maptiler.com/sdk-js/api-reference/interfaces/Externals.EventEmitter.EventEmitterEventMap/)\[[E](https://docs.maptiler.com/sdk-js/api-reference/classes/SdkConfig/#emite)\] : any\[\],  
        \>
    
    #### Returns boolean
    
    #### Since[](#since-2)
    
    v0.1.26
    

### eventNames[](#eventnames)

-   eventNames(): (string | symbol)\[\][](#eventnames-1)
    
    Returns an array listing the events for which the emitter has registered listeners.
    
    ```typescript
    import { EventEmitter } from 'node:events';
    
    const myEE = new EventEmitter();
    myEE.on('foo', () => {});
    myEE.on('bar', () => {});
    
    const sym = Symbol('symbol');
    myEE.on(sym, () => {});
    
    console.log(myEE.eventNames());
    // Prints: [ 'foo', 'bar', Symbol(symbol) ]
    ```
    
    #### Returns (string | symbol)\[\]
    
    #### Since[](#since-3)
    
    v6.0.0
    

### getMaxListeners[](#getmaxlisteners)

-   getMaxListeners(): number[](#getmaxlisteners-1)
    
    Returns the current max listener value for the `EventEmitter` which is either set by `emitter.setMaxListeners(n)` or defaults to `events.defaultMaxListeners`.
    
    #### Returns number
    
    #### Since[](#since-4)
    
    v1.0.0
    

### listenerCount[](#listenercount)

-   listenerCount<[E](#listenercounte) extends string | symbol\>(  
        eventName: [IfEventMap](https://docs.maptiler.com/sdk-js/api-reference/types/Externals.IfEventMap/)<  
            [T](#t),  
            (keyof EventEmitterEventMap)  
            | (keyof T & (string | symbol))  
            | [E](https://docs.maptiler.com/sdk-js/api-reference/classes/SdkConfig/#listenercounte),  
        \>,  
        listener?: [IfEventMap](https://docs.maptiler.com/sdk-js/api-reference/types/Externals.IfEventMap/)<  
            [T](#t),  
            (  
                ...args: [E](https://docs.maptiler.com/sdk-js/api-reference/classes/SdkConfig/#listenercounte) extends keyof [T](#t)  
                    ? [T](#t)\[[E](https://docs.maptiler.com/sdk-js/api-reference/classes/SdkConfig/#listenercounte)\]  
                    : [E](https://docs.maptiler.com/sdk-js/api-reference/classes/SdkConfig/#listenercounte) extends keyof [EventEmitterEventMap](https://docs.maptiler.com/sdk-js/api-reference/interfaces/Externals.EventEmitter.EventEmitterEventMap/) ? [EventEmitterEventMap](https://docs.maptiler.com/sdk-js/api-reference/interfaces/Externals.EventEmitter.EventEmitterEventMap/)\[[E](https://docs.maptiler.com/sdk-js/api-reference/classes/SdkConfig/#listenercounte)\] : any\[\],  
            ) \=> void,  
            (...args: any\[\]) \=> void,  
        \>,  
    ): number[](#listenercount-1)
    
    Returns the number of listeners listening for the event named `eventName`. If `listener` is provided, it will return how many times the listener is found in the list of the listeners of the event.
    
    #### Type Parameters
    
    -   E extends string | symbol
    
    #### Parameters
    
    -   eventName: [IfEventMap](https://docs.maptiler.com/sdk-js/api-reference/types/Externals.IfEventMap/)<[T](#t), (keyof EventEmitterEventMap) | (keyof T & (string | symbol)) | [E](https://docs.maptiler.com/sdk-js/api-reference/classes/SdkConfig/#listenercounte)\>
        
        The name of the event being listened for
        
    -   `Optional`listener: [IfEventMap](https://docs.maptiler.com/sdk-js/api-reference/types/Externals.IfEventMap/)<  
            [T](#t),  
            (  
                ...args: [E](https://docs.maptiler.com/sdk-js/api-reference/classes/SdkConfig/#listenercounte) extends keyof [T](#t)  
                    ? [T](#t)\[[E](https://docs.maptiler.com/sdk-js/api-reference/classes/SdkConfig/#listenercounte)\]  
                    : [E](https://docs.maptiler.com/sdk-js/api-reference/classes/SdkConfig/#listenercounte) extends keyof [EventEmitterEventMap](https://docs.maptiler.com/sdk-js/api-reference/interfaces/Externals.EventEmitter.EventEmitterEventMap/) ? [EventEmitterEventMap](https://docs.maptiler.com/sdk-js/api-reference/interfaces/Externals.EventEmitter.EventEmitterEventMap/)\[[E](https://docs.maptiler.com/sdk-js/api-reference/classes/SdkConfig/#listenercounte)\] : any\[\],  
            ) \=> void,  
            (...args: any\[\]) \=> void,  
        \>
        
        The event handler function
        
    
    #### Returns number
    
    #### Since[](#since-5)
    
    v3.2.0
    

### listeners[](#listeners)

-   listeners<[E](#listenerse) extends string | symbol\>(  
        eventName: [IfEventMap](https://docs.maptiler.com/sdk-js/api-reference/types/Externals.IfEventMap/)<  
            [T](#t),  
            (keyof EventEmitterEventMap)  
            | (keyof T & (string | symbol))  
            | [E](https://docs.maptiler.com/sdk-js/api-reference/classes/SdkConfig/#listenerse),  
        \>,  
    ): [IfEventMap](https://docs.maptiler.com/sdk-js/api-reference/types/Externals.IfEventMap/)<  
        [T](#t),  
        (  
            ...args: [E](https://docs.maptiler.com/sdk-js/api-reference/classes/SdkConfig/#listenerse) extends keyof [T](#t)  
                ? [T](#t)\[[E](https://docs.maptiler.com/sdk-js/api-reference/classes/SdkConfig/#listenerse)\]  
                : [E](https://docs.maptiler.com/sdk-js/api-reference/classes/SdkConfig/#listenerse) extends keyof [EventEmitterEventMap](https://docs.maptiler.com/sdk-js/api-reference/interfaces/Externals.EventEmitter.EventEmitterEventMap/) ? [EventEmitterEventMap](https://docs.maptiler.com/sdk-js/api-reference/interfaces/Externals.EventEmitter.EventEmitterEventMap/)\[[E](https://docs.maptiler.com/sdk-js/api-reference/classes/SdkConfig/#listenerse)\] : any\[\],  
        ) \=> void,  
        (...args: any\[\]) \=> void,  
    \>\[\][](#listeners-1)
    
    Returns a copy of the array of listeners for the event named `eventName`.
    
    ```typescript
    server.on('connection', (stream) => {
      console.log('someone connected!');
    });
    console.log(util.inspect(server.listeners('connection')));
    // Prints: [ [Function] ]
    ```
    
    #### Type Parameters
    
    -   E extends string | symbol
    
    #### Parameters
    
    -   eventName: [IfEventMap](https://docs.maptiler.com/sdk-js/api-reference/types/Externals.IfEventMap/)<[T](#t), (keyof EventEmitterEventMap) | (keyof T & (string | symbol)) | [E](https://docs.maptiler.com/sdk-js/api-reference/classes/SdkConfig/#listenerse)\>
    
    #### Returns [IfEventMap](https://docs.maptiler.com/sdk-js/api-reference/types/Externals.IfEventMap/)<  
        [T](#t),  
        (  
            ...args: [E](https://docs.maptiler.com/sdk-js/api-reference/classes/SdkConfig/#listenerse) extends keyof [T](#t)  
                ? [T](#t)\[[E](https://docs.maptiler.com/sdk-js/api-reference/classes/SdkConfig/#listenerse)\]  
                : [E](https://docs.maptiler.com/sdk-js/api-reference/classes/SdkConfig/#listenerse) extends keyof [EventEmitterEventMap](https://docs.maptiler.com/sdk-js/api-reference/interfaces/Externals.EventEmitter.EventEmitterEventMap/) ? [EventEmitterEventMap](https://docs.maptiler.com/sdk-js/api-reference/interfaces/Externals.EventEmitter.EventEmitterEventMap/)\[[E](https://docs.maptiler.com/sdk-js/api-reference/classes/SdkConfig/#listenerse)\] : any\[\],  
        ) \=> void,  
        (...args: any\[\]) \=> void,  
    \>\[\]
    
    #### Since[](#since-6)
    
    v0.1.26
    

### off[](#off)

-   off<[E](#offe) extends string | symbol\>(  
        eventName: [IfEventMap](https://docs.maptiler.com/sdk-js/api-reference/types/Externals.IfEventMap/)<  
            [T](#t),  
            (keyof EventEmitterEventMap)  
            | (keyof T & (string | symbol))  
            | [E](https://docs.maptiler.com/sdk-js/api-reference/classes/SdkConfig/#offe),  
        \>,  
        listener: [IfEventMap](https://docs.maptiler.com/sdk-js/api-reference/types/Externals.IfEventMap/)<  
            [T](#t),  
            (  
                ...args: [E](https://docs.maptiler.com/sdk-js/api-reference/classes/SdkConfig/#offe) extends keyof [T](#t)  
                    ? [T](#t)\[[E](https://docs.maptiler.com/sdk-js/api-reference/classes/SdkConfig/#offe)\]  
                    : [E](https://docs.maptiler.com/sdk-js/api-reference/classes/SdkConfig/#offe) extends keyof [EventEmitterEventMap](https://docs.maptiler.com/sdk-js/api-reference/interfaces/Externals.EventEmitter.EventEmitterEventMap/) ? [EventEmitterEventMap](https://docs.maptiler.com/sdk-js/api-reference/interfaces/Externals.EventEmitter.EventEmitterEventMap/)\[[E](https://docs.maptiler.com/sdk-js/api-reference/classes/SdkConfig/#offe)\] : any\[\],  
            ) \=> void,  
        \>,  
    ): this[](#off-1)
    
    Alias for `emitter.removeListener()`.
    
    #### Type Parameters
    
    -   E extends string | symbol
    
    #### Parameters
    
    -   eventName: [IfEventMap](https://docs.maptiler.com/sdk-js/api-reference/types/Externals.IfEventMap/)<[T](#t), (keyof EventEmitterEventMap) | (keyof T & (string | symbol)) | [E](https://docs.maptiler.com/sdk-js/api-reference/classes/SdkConfig/#offe)\>
    -   listener: [IfEventMap](https://docs.maptiler.com/sdk-js/api-reference/types/Externals.IfEventMap/)<  
            [T](#t),  
            (  
                ...args: [E](https://docs.maptiler.com/sdk-js/api-reference/classes/SdkConfig/#offe) extends keyof [T](#t)  
                    ? [T](#t)\[[E](https://docs.maptiler.com/sdk-js/api-reference/classes/SdkConfig/#offe)\]  
                    : [E](https://docs.maptiler.com/sdk-js/api-reference/classes/SdkConfig/#offe) extends keyof [EventEmitterEventMap](https://docs.maptiler.com/sdk-js/api-reference/interfaces/Externals.EventEmitter.EventEmitterEventMap/) ? [EventEmitterEventMap](https://docs.maptiler.com/sdk-js/api-reference/interfaces/Externals.EventEmitter.EventEmitterEventMap/)\[[E](https://docs.maptiler.com/sdk-js/api-reference/classes/SdkConfig/#offe)\] : any\[\],  
            ) \=> void,  
        \>
    
    #### Returns this
    
    #### Since[](#since-7)
    
    v10.0.0
    

### on[](#on)

-   on<[E](#one) extends string | symbol\>(  
        eventName: [IfEventMap](https://docs.maptiler.com/sdk-js/api-reference/types/Externals.IfEventMap/)<  
            [T](#t),  
            (keyof EventEmitterEventMap)  
            | (keyof T & (string | symbol))  
            | [E](https://docs.maptiler.com/sdk-js/api-reference/classes/SdkConfig/#one),  
        \>,  
        listener: [IfEventMap](https://docs.maptiler.com/sdk-js/api-reference/types/Externals.IfEventMap/)<  
            [T](#t),  
            (  
                ...args: [E](https://docs.maptiler.com/sdk-js/api-reference/classes/SdkConfig/#one) extends keyof [T](#t)  
                    ? [T](#t)\[[E](https://docs.maptiler.com/sdk-js/api-reference/classes/SdkConfig/#one)\]  
                    : [E](https://docs.maptiler.com/sdk-js/api-reference/classes/SdkConfig/#one) extends keyof [EventEmitterEventMap](https://docs.maptiler.com/sdk-js/api-reference/interfaces/Externals.EventEmitter.EventEmitterEventMap/) ? [EventEmitterEventMap](https://docs.maptiler.com/sdk-js/api-reference/interfaces/Externals.EventEmitter.EventEmitterEventMap/)\[[E](https://docs.maptiler.com/sdk-js/api-reference/classes/SdkConfig/#one)\] : any\[\],  
            ) \=> void,  
        \>,  
    ): this[](#on-1)
    
    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 already been added. Multiple calls passing the same combination of `eventName` and `listener` will result in the `listener` being added, and called, multiple times.
    
    ```typescript
    server.on('connection', (stream) => {
      console.log('someone connected!');
    });
    ```
    
    Returns a reference to the `EventEmitter`, so that calls can be chained.
    
    By default, event listeners are invoked in the order they are added. The `emitter.prependListener()` method can be used as an alternative to add the event listener to the beginning of the listeners array.
    
    ```typescript
    import { EventEmitter } from 'node:events';
    const myEE = new EventEmitter();
    myEE.on('foo', () => console.log('a'));
    myEE.prependListener('foo', () => console.log('b'));
    myEE.emit('foo');
    // Prints:
    //   b
    //   a
    ```
    
    #### Type Parameters
    
    -   E extends string | symbol
    
    #### Parameters
    
    -   eventName: [IfEventMap](https://docs.maptiler.com/sdk-js/api-reference/types/Externals.IfEventMap/)<[T](#t), (keyof EventEmitterEventMap) | (keyof T & (string | symbol)) | [E](https://docs.maptiler.com/sdk-js/api-reference/classes/SdkConfig/#one)\>
        
        The name of the event.
        
    -   listener: [IfEventMap](https://docs.maptiler.com/sdk-js/api-reference/types/Externals.IfEventMap/)<  
            [T](#t),  
            (  
                ...args: [E](https://docs.maptiler.com/sdk-js/api-reference/classes/SdkConfig/#one) extends keyof [T](#t)  
                    ? [T](#t)\[[E](https://docs.maptiler.com/sdk-js/api-reference/classes/SdkConfig/#one)\]  
                    : [E](https://docs.maptiler.com/sdk-js/api-reference/classes/SdkConfig/#one) extends keyof [EventEmitterEventMap](https://docs.maptiler.com/sdk-js/api-reference/interfaces/Externals.EventEmitter.EventEmitterEventMap/) ? [EventEmitterEventMap](https://docs.maptiler.com/sdk-js/api-reference/interfaces/Externals.EventEmitter.EventEmitterEventMap/)\[[E](https://docs.maptiler.com/sdk-js/api-reference/classes/SdkConfig/#one)\] : any\[\],  
            ) \=> void,  
        \>
        
        The callback function
        
    
    #### Returns this
    
    #### Since[](#since-8)
    
    v0.1.101
    

### once[](#once)

-   once<[E](#oncee) extends string | symbol\>(  
        eventName: [IfEventMap](https://docs.maptiler.com/sdk-js/api-reference/types/Externals.IfEventMap/)<  
            [T](#t),  
            (keyof EventEmitterEventMap)  
            | (keyof T & (string | symbol))  
            | [E](https://docs.maptiler.com/sdk-js/api-reference/classes/SdkConfig/#oncee),  
        \>,  
        listener: [IfEventMap](https://docs.maptiler.com/sdk-js/api-reference/types/Externals.IfEventMap/)<  
            [T](#t),  
            (  
                ...args: [E](https://docs.maptiler.com/sdk-js/api-reference/classes/SdkConfig/#oncee) extends keyof [T](#t)  
                    ? [T](#t)\[[E](https://docs.maptiler.com/sdk-js/api-reference/classes/SdkConfig/#oncee)\]  
                    : [E](https://docs.maptiler.com/sdk-js/api-reference/classes/SdkConfig/#oncee) extends keyof [EventEmitterEventMap](https://docs.maptiler.com/sdk-js/api-reference/interfaces/Externals.EventEmitter.EventEmitterEventMap/) ? [EventEmitterEventMap](https://docs.maptiler.com/sdk-js/api-reference/interfaces/Externals.EventEmitter.EventEmitterEventMap/)\[[E](https://docs.maptiler.com/sdk-js/api-reference/classes/SdkConfig/#oncee)\] : any\[\],  
            ) \=> void,  
        \>,  
    ): this[](#once-1)
    
    Adds a **one-time** `listener` function for the event named `eventName`. The next time `eventName` is triggered, this listener is removed and then invoked.
    
    ```typescript
    server.once('connection', (stream) => {
      console.log('Ah, we have our first user!');
    });
    ```
    
    Returns a reference to the `EventEmitter`, so that calls can be chained.
    
    By default, event listeners are invoked in the order they are added. The `emitter.prependOnceListener()` method can be used as an alternative to add the event listener to the beginning of the listeners array.
    
    ```typescript
    import { EventEmitter } from 'node:events';
    const myEE = new EventEmitter();
    myEE.once('foo', () => console.log('a'));
    myEE.prependOnceListener('foo', () => console.log('b'));
    myEE.emit('foo');
    // Prints:
    //   b
    //   a
    ```
    
    #### Type Parameters
    
    -   E extends string | symbol
    
    #### Parameters
    
    -   eventName: [IfEventMap](https://docs.maptiler.com/sdk-js/api-reference/types/Externals.IfEventMap/)<[T](#t), (keyof EventEmitterEventMap) | (keyof T & (string | symbol)) | [E](https://docs.maptiler.com/sdk-js/api-reference/classes/SdkConfig/#oncee)\>
        
        The name of the event.
        
    -   listener: [IfEventMap](https://docs.maptiler.com/sdk-js/api-reference/types/Externals.IfEventMap/)<  
            [T](#t),  
            (  
                ...args: [E](https://docs.maptiler.com/sdk-js/api-reference/classes/SdkConfig/#oncee) extends keyof [T](#t)  
                    ? [T](#t)\[[E](https://docs.maptiler.com/sdk-js/api-reference/classes/SdkConfig/#oncee)\]  
                    : [E](https://docs.maptiler.com/sdk-js/api-reference/classes/SdkConfig/#oncee) extends keyof [EventEmitterEventMap](https://docs.maptiler.com/sdk-js/api-reference/interfaces/Externals.EventEmitter.EventEmitterEventMap/) ? [EventEmitterEventMap](https://docs.maptiler.com/sdk-js/api-reference/interfaces/Externals.EventEmitter.EventEmitterEventMap/)\[[E](https://docs.maptiler.com/sdk-js/api-reference/classes/SdkConfig/#oncee)\] : any\[\],  
            ) \=> void,  
        \>
        
        The callback function
        
    
    #### Returns this
    
    #### Since[](#since-9)
    
    v0.3.0
    

### prependListener[](#prependlistener)

-   prependListener<[E](#prependlistenere) extends string | symbol\>(  
        eventName: [IfEventMap](https://docs.maptiler.com/sdk-js/api-reference/types/Externals.IfEventMap/)<  
            [T](#t),  
            (keyof EventEmitterEventMap)  
            | (keyof T & (string | symbol))  
            | [E](https://docs.maptiler.com/sdk-js/api-reference/classes/SdkConfig/#prependlistenere),  
        \>,  
        listener: [IfEventMap](https://docs.maptiler.com/sdk-js/api-reference/types/Externals.IfEventMap/)<  
            [T](#t),  
            (  
                ...args: [E](https://docs.maptiler.com/sdk-js/api-reference/classes/SdkConfig/#prependlistenere) extends keyof [T](#t)  
                    ? [T](#t)\[[E](https://docs.maptiler.com/sdk-js/api-reference/classes/SdkConfig/#prependlistenere)\]  
                    : [E](https://docs.maptiler.com/sdk-js/api-reference/classes/SdkConfig/#prependlistenere) extends keyof [EventEmitterEventMap](https://docs.maptiler.com/sdk-js/api-reference/interfaces/Externals.EventEmitter.EventEmitterEventMap/) ? [EventEmitterEventMap](https://docs.maptiler.com/sdk-js/api-reference/interfaces/Externals.EventEmitter.EventEmitterEventMap/)\[[E](https://docs.maptiler.com/sdk-js/api-reference/classes/SdkConfig/#prependlistenere)\] : any\[\],  
            ) \=> void,  
        \>,  
    ): this[](#prependlistener-1)
    
    Adds the `listener` function to the _beginning_ of the listeners array for the event named `eventName`. No checks are made to see if the `listener` has already been added. Multiple calls passing the same combination of `eventName` and `listener` will result in the `listener` being added, and called, multiple times.
    
    ```typescript
    server.prependListener('connection', (stream) => {
      console.log('someone connected!');
    });
    ```
    
    Returns a reference to the `EventEmitter`, so that calls can be chained.
    
    #### Type Parameters
    
    -   E extends string | symbol
    
    #### Parameters
    
    -   eventName: [IfEventMap](https://docs.maptiler.com/sdk-js/api-reference/types/Externals.IfEventMap/)<[T](#t), (keyof EventEmitterEventMap) | (keyof T & (string | symbol)) | [E](https://docs.maptiler.com/sdk-js/api-reference/classes/SdkConfig/#prependlistenere)\>
        
        The name of the event.
        
    -   listener: [IfEventMap](https://docs.maptiler.com/sdk-js/api-reference/types/Externals.IfEventMap/)<  
            [T](#t),  
            (  
                ...args: [E](https://docs.maptiler.com/sdk-js/api-reference/classes/SdkConfig/#prependlistenere) extends keyof [T](#t)  
                    ? [T](#t)\[[E](https://docs.maptiler.com/sdk-js/api-reference/classes/SdkConfig/#prependlistenere)\]  
                    : [E](https://docs.maptiler.com/sdk-js/api-reference/classes/SdkConfig/#prependlistenere) extends keyof [EventEmitterEventMap](https://docs.maptiler.com/sdk-js/api-reference/interfaces/Externals.EventEmitter.EventEmitterEventMap/) ? [EventEmitterEventMap](https://docs.maptiler.com/sdk-js/api-reference/interfaces/Externals.EventEmitter.EventEmitterEventMap/)\[[E](https://docs.maptiler.com/sdk-js/api-reference/classes/SdkConfig/#prependlistenere)\] : any\[\],  
            ) \=> void,  
        \>
        
        The callback function
        
    
    #### Returns this
    
    #### Since[](#since-10)
    
    v6.0.0
    

### prependOnceListener[](#prependoncelistener)

-   prependOnceListener<[E](#prependoncelistenere) extends string | symbol\>(  
        eventName: [IfEventMap](https://docs.maptiler.com/sdk-js/api-reference/types/Externals.IfEventMap/)<  
            [T](#t),  
            (keyof EventEmitterEventMap)  
            | (keyof T & (string | symbol))  
            | [E](https://docs.maptiler.com/sdk-js/api-reference/classes/SdkConfig/#prependoncelistenere),  
        \>,  
        listener: [IfEventMap](https://docs.maptiler.com/sdk-js/api-reference/types/Externals.IfEventMap/)<  
            [T](#t),  
            (  
                ...args: [E](https://docs.maptiler.com/sdk-js/api-reference/classes/SdkConfig/#prependoncelistenere) extends keyof [T](#t)  
                    ? [T](#t)\[[E](https://docs.maptiler.com/sdk-js/api-reference/classes/SdkConfig/#prependoncelistenere)\]  
                    : [E](https://docs.maptiler.com/sdk-js/api-reference/classes/SdkConfig/#prependoncelistenere) extends keyof [EventEmitterEventMap](https://docs.maptiler.com/sdk-js/api-reference/interfaces/Externals.EventEmitter.EventEmitterEventMap/) ? [EventEmitterEventMap](https://docs.maptiler.com/sdk-js/api-reference/interfaces/Externals.EventEmitter.EventEmitterEventMap/)\[[E](https://docs.maptiler.com/sdk-js/api-reference/classes/SdkConfig/#prependoncelistenere)\] : any\[\],  
            ) \=> void,  
        \>,  
    ): this[](#prependoncelistener-1)
    
    Adds a **one-time** `listener` function for the event named `eventName` to the _beginning_ of the listeners array. The next time `eventName` is triggered, this listener is removed, and then invoked.
    
    ```typescript
    server.prependOnceListener('connection', (stream) => {
      console.log('Ah, we have our first user!');
    });
    ```
    
    Returns a reference to the `EventEmitter`, so that calls can be chained.
    
    #### Type Parameters
    
    -   E extends string | symbol
    
    #### Parameters
    
    -   eventName: [IfEventMap](https://docs.maptiler.com/sdk-js/api-reference/types/Externals.IfEventMap/)<[T](#t), (keyof EventEmitterEventMap) | (keyof T & (string | symbol)) | [E](https://docs.maptiler.com/sdk-js/api-reference/classes/SdkConfig/#prependoncelistenere)\>
        
        The name of the event.
        
    -   listener: [IfEventMap](https://docs.maptiler.com/sdk-js/api-reference/types/Externals.IfEventMap/)<  
            [T](#t),  
            (  
                ...args: [E](https://docs.maptiler.com/sdk-js/api-reference/classes/SdkConfig/#prependoncelistenere) extends keyof [T](#t)  
                    ? [T](#t)\[[E](https://docs.maptiler.com/sdk-js/api-reference/classes/SdkConfig/#prependoncelistenere)\]  
                    : [E](https://docs.maptiler.com/sdk-js/api-reference/classes/SdkConfig/#prependoncelistenere) extends keyof [EventEmitterEventMap](https://docs.maptiler.com/sdk-js/api-reference/interfaces/Externals.EventEmitter.EventEmitterEventMap/) ? [EventEmitterEventMap](https://docs.maptiler.com/sdk-js/api-reference/interfaces/Externals.EventEmitter.EventEmitterEventMap/)\[[E](https://docs.maptiler.com/sdk-js/api-reference/classes/SdkConfig/#prependoncelistenere)\] : any\[\],  
            ) \=> void,  
        \>
        
        The callback function
        
    
    #### Returns this
    
    #### Since[](#since-11)
    
    v6.0.0
    

### rawListeners[](#rawlisteners)

-   rawListeners<[E](#rawlistenerse) extends string | symbol\>(  
        eventName: [IfEventMap](https://docs.maptiler.com/sdk-js/api-reference/types/Externals.IfEventMap/)<  
            [T](#t),  
            (keyof EventEmitterEventMap)  
            | (keyof T & (string | symbol))  
            | [E](https://docs.maptiler.com/sdk-js/api-reference/classes/SdkConfig/#rawlistenerse),  
        \>,  
    ): [IfEventMap](https://docs.maptiler.com/sdk-js/api-reference/types/Externals.IfEventMap/)<  
        [T](#t),  
        (  
            ...args: [E](https://docs.maptiler.com/sdk-js/api-reference/classes/SdkConfig/#rawlistenerse) extends keyof [T](#t)  
                ? [T](#t)\[[E](https://docs.maptiler.com/sdk-js/api-reference/classes/SdkConfig/#rawlistenerse)\]  
                : [E](https://docs.maptiler.com/sdk-js/api-reference/classes/SdkConfig/#rawlistenerse) extends keyof [EventEmitterEventMap](https://docs.maptiler.com/sdk-js/api-reference/interfaces/Externals.EventEmitter.EventEmitterEventMap/) ? [EventEmitterEventMap](https://docs.maptiler.com/sdk-js/api-reference/interfaces/Externals.EventEmitter.EventEmitterEventMap/)\[[E](https://docs.maptiler.com/sdk-js/api-reference/classes/SdkConfig/#rawlistenerse)\] : any\[\],  
        ) \=> void,  
        (...args: any\[\]) \=> void,  
    \>\[\][](#rawlisteners-1)
    
    Returns a copy of the array of listeners for the event named `eventName`, including any wrappers (such as those created by `.once()`).
    
    ```typescript
    import { EventEmitter } from 'node:events';
    const emitter = new EventEmitter();
    emitter.once('log', () => console.log('log once'));
    
    // Returns a new Array with a function `onceWrapper` which has a property
    // `listener` which contains the original listener bound above
    const listeners = emitter.rawListeners('log');
    const logFnWrapper = listeners[0];
    
    // Logs "log once" to the console and does not unbind the `once` event
    logFnWrapper.listener();
    
    // Logs "log once" to the console and removes the listener
    logFnWrapper();
    
    emitter.on('log', () => console.log('log persistently'));
    // Will return a new Array with a single function bound by `.on()` above
    const newListeners = emitter.rawListeners('log');
    
    // Logs "log persistently" twice
    newListeners[0]();
    emitter.emit('log');
    ```
    
    #### Type Parameters
    
    -   E extends string | symbol
    
    #### Parameters
    
    -   eventName: [IfEventMap](https://docs.maptiler.com/sdk-js/api-reference/types/Externals.IfEventMap/)<[T](#t), (keyof EventEmitterEventMap) | (keyof T & (string | symbol)) | [E](https://docs.maptiler.com/sdk-js/api-reference/classes/SdkConfig/#rawlistenerse)\>
    
    #### Returns [IfEventMap](https://docs.maptiler.com/sdk-js/api-reference/types/Externals.IfEventMap/)<  
        [T](#t),  
        (  
            ...args: [E](https://docs.maptiler.com/sdk-js/api-reference/classes/SdkConfig/#rawlistenerse) extends keyof [T](#t)  
                ? [T](#t)\[[E](https://docs.maptiler.com/sdk-js/api-reference/classes/SdkConfig/#rawlistenerse)\]  
                : [E](https://docs.maptiler.com/sdk-js/api-reference/classes/SdkConfig/#rawlistenerse) extends keyof [EventEmitterEventMap](https://docs.maptiler.com/sdk-js/api-reference/interfaces/Externals.EventEmitter.EventEmitterEventMap/) ? [EventEmitterEventMap](https://docs.maptiler.com/sdk-js/api-reference/interfaces/Externals.EventEmitter.EventEmitterEventMap/)\[[E](https://docs.maptiler.com/sdk-js/api-reference/classes/SdkConfig/#rawlistenerse)\] : any\[\],  
        ) \=> void,  
        (...args: any\[\]) \=> void,  
    \>\[\]
    
    #### Since[](#since-12)
    
    v9.4.0
    

### removeAllListeners[](#removealllisteners)

-   removeAllListeners<[E](#removealllistenerse) extends string | symbol\>(  
        eventName?: [IfEventMap](https://docs.maptiler.com/sdk-js/api-reference/types/Externals.IfEventMap/)<  
            [T](#t),  
            (keyof EventEmitterEventMap)  
            | (keyof T & (string | symbol))  
            | [E](https://docs.maptiler.com/sdk-js/api-reference/classes/SdkConfig/#removealllistenerse),  
            string | symbol,  
        \>,  
    ): this[](#removealllisteners-1)
    
    Removes all listeners, or those of the specified `eventName`.
    
    It is bad practice to remove listeners added elsewhere in the code, particularly when the `EventEmitter` instance was created by some other component or module (e.g. sockets or file streams).
    
    Returns a reference to the `EventEmitter`, so that calls can be chained.
    
    #### Type Parameters
    
    -   E extends string | symbol
    
    #### Parameters
    
    -   `Optional`eventName: [IfEventMap](https://docs.maptiler.com/sdk-js/api-reference/types/Externals.IfEventMap/)<  
            [T](#t),  
            (keyof EventEmitterEventMap)  
            | (keyof T & (string | symbol))  
            | [E](https://docs.maptiler.com/sdk-js/api-reference/classes/SdkConfig/#removealllistenerse),  
            string | symbol,  
        \>
    
    #### Returns this
    
    #### Since[](#since-13)
    
    v0.1.26
    

### removeListener[](#removelistener)

-   removeListener<[E](#removelistenere) extends string | symbol\>(  
        eventName: [IfEventMap](https://docs.maptiler.com/sdk-js/api-reference/types/Externals.IfEventMap/)<  
            [T](#t),  
            (keyof EventEmitterEventMap)  
            | (keyof T & (string | symbol))  
            | [E](https://docs.maptiler.com/sdk-js/api-reference/classes/SdkConfig/#removelistenere),  
        \>,  
        listener: [IfEventMap](https://docs.maptiler.com/sdk-js/api-reference/types/Externals.IfEventMap/)<  
            [T](#t),  
            (  
                ...args: [E](https://docs.maptiler.com/sdk-js/api-reference/classes/SdkConfig/#removelistenere) extends keyof [T](#t)  
                    ? [T](#t)\[[E](https://docs.maptiler.com/sdk-js/api-reference/classes/SdkConfig/#removelistenere)\]  
                    : [E](https://docs.maptiler.com/sdk-js/api-reference/classes/SdkConfig/#removelistenere) extends keyof [EventEmitterEventMap](https://docs.maptiler.com/sdk-js/api-reference/interfaces/Externals.EventEmitter.EventEmitterEventMap/) ? [EventEmitterEventMap](https://docs.maptiler.com/sdk-js/api-reference/interfaces/Externals.EventEmitter.EventEmitterEventMap/)\[[E](https://docs.maptiler.com/sdk-js/api-reference/classes/SdkConfig/#removelistenere)\] : any\[\],  
            ) \=> void,  
        \>,  
    ): this[](#removelistener-1)
    
    Removes the specified `listener` from the listener array for the event named `eventName`.
    
    ```typescript
    const callback = (stream) => {
      console.log('someone connected!');
    };
    server.on('connection', callback);
    // ...
    server.removeListener('connection', callback);
    ```
    
    `removeListener()` will remove, at most, one instance of a listener from the listener array. If any single listener has been added multiple times to the listener array for the specified `eventName`, then `removeListener()` must be called multiple times to remove each instance.
    
    Once an event is emitted, all listeners attached to it at the time of emitting are called in order. This implies that any `removeListener()` or `removeAllListeners()` calls _after_ emitting and _before_ the last listener finishes execution will not remove them from `emit()` in progress. Subsequent events behave as expected.
    
    ```typescript
    import { EventEmitter } from 'node:events';
    class MyEmitter extends EventEmitter {}
    const myEmitter = new MyEmitter();
    
    const callbackA = () => {
      console.log('A');
      myEmitter.removeListener('event', callbackB);
    };
    
    const callbackB = () => {
      console.log('B');
    };
    
    myEmitter.on('event', callbackA);
    
    myEmitter.on('event', callbackB);
    
    // callbackA removes listener callbackB but it will still be called.
    // Internal listener array at time of emit [callbackA, callbackB]
    myEmitter.emit('event');
    // Prints:
    //   A
    //   B
    
    // callbackB is now removed.
    // Internal listener array [callbackA]
    myEmitter.emit('event');
    // Prints:
    //   A
    ```
    
    Because listeners are managed using an internal array, calling this will change the position indexes of any listener registered _after_ the listener being removed. This will not impact the order in which listeners are called, but it means that any copies of the listener array as returned by the `emitter.listeners()` method will need to be recreated.
    
    When a single function has been added as a handler multiple times for a single event (as in the example below), `removeListener()` will remove the most recently added instance. In the example the `once('ping')` listener is removed:
    
    ```typescript
    import { EventEmitter } from 'node:events';
    const ee = new EventEmitter();
    
    function pong() {
      console.log('pong');
    }
    
    ee.on('ping', pong);
    ee.once('ping', pong);
    ee.removeListener('ping', pong);
    
    ee.emit('ping');
    ee.emit('ping');
    ```
    
    Returns a reference to the `EventEmitter`, so that calls can be chained.
    
    #### Type Parameters
    
    -   E extends string | symbol
    
    #### Parameters
    
    -   eventName: [IfEventMap](https://docs.maptiler.com/sdk-js/api-reference/types/Externals.IfEventMap/)<[T](#t), (keyof EventEmitterEventMap) | (keyof T & (string | symbol)) | [E](https://docs.maptiler.com/sdk-js/api-reference/classes/SdkConfig/#removelistenere)\>
    -   listener: [IfEventMap](https://docs.maptiler.com/sdk-js/api-reference/types/Externals.IfEventMap/)<  
            [T](#t),  
            (  
                ...args: [E](https://docs.maptiler.com/sdk-js/api-reference/classes/SdkConfig/#removelistenere) extends keyof [T](#t)  
                    ? [T](#t)\[[E](https://docs.maptiler.com/sdk-js/api-reference/classes/SdkConfig/#removelistenere)\]  
                    : [E](https://docs.maptiler.com/sdk-js/api-reference/classes/SdkConfig/#removelistenere) extends keyof [EventEmitterEventMap](https://docs.maptiler.com/sdk-js/api-reference/interfaces/Externals.EventEmitter.EventEmitterEventMap/) ? [EventEmitterEventMap](https://docs.maptiler.com/sdk-js/api-reference/interfaces/Externals.EventEmitter.EventEmitterEventMap/)\[[E](https://docs.maptiler.com/sdk-js/api-reference/classes/SdkConfig/#removelistenere)\] : any\[\],  
            ) \=> void,  
        \>
    
    #### Returns this
    
    #### Since[](#since-14)
    
    v0.1.26
    

### setMaxListeners[](#setmaxlisteners)

-   setMaxListeners(n: number): this[](#setmaxlisteners-1)
    
    By default `EventEmitter`s will print a warning if more than `10` listeners are added for a particular event. This is a useful default that helps finding memory leaks. The `emitter.setMaxListeners()` method allows the limit to be modified for this specific `EventEmitter` instance. The value can be set to `Infinity` (or `0`) to indicate an unlimited number of listeners.
    
    Returns a reference to the `EventEmitter`, so that calls can be chained.
    
    #### Parameters
    
    -   n: number
    
    #### Returns this
    
    #### Since[](#since-15)
    
    v0.3.5