--- title: "SdkConfig | 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. # Class SdkConfig`Maptiler` Configuration class for the SDK #### Hierarchy ([View Summary](https://docs.maptiler.com/sdk-js/api-reference/hierarchy/#SdkConfig)) - [EventEmitter](https://docs.maptiler.com/sdk-js/api-reference/classes/Externals.EventEmitter/) - SdkConfig ##### Index ### Constructors[](#constructors) [constructor](#constructor) ### Properties[](#properties) [caching](#caching) [primaryLanguage](#primarylanguage) [secondaryLanguage?](#secondarylanguage) [session](#session) [telemetry](#telemetry) ### Accessors[](#accessors) [apiHost](#apihost) [apiKey](#apikey) [apiURL](#apiurl) [experimental\_defaultPathSampleSteps](#experimental_defaultpathsamplesteps) [experimental\_defaultWorkerCount](#experimental_defaultworkercount) [fetch](#fetch) [unit](#unit) [useEuEndpoints](#useeuendpoints) ### 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) ## Constructors[](#constructors-1) ### constructor[](#constructor) - new SdkConfig(options?: [EventEmitterOptions](https://docs.maptiler.com/sdk-js/api-reference/interfaces/Externals.EventEmitterOptions/)): SdkConfig[](#constructorsdkconfig) #### Parameters - `Optional`options: [EventEmitterOptions](https://docs.maptiler.com/sdk-js/api-reference/interfaces/Externals.EventEmitterOptions/) #### Returns SdkConfig Inherited from [EventEmitter](https://docs.maptiler.com/sdk-js/api-reference/classes/Externals.EventEmitter/).[constructor](https://docs.maptiler.com/sdk-js/api-reference/classes/Externals.EventEmitter/#constructor) ## Properties[](#properties-1) ### `Maptiler`caching[](#caching) caching: boolean = true Enables client-side caching of requests for tiles and fonts. The cached requests persist multiple browser sessions and will be reused when possible. Works only for requests to the MapTiler Cloud API when sessions are enabled. ### `Maptiler`primaryLanguage[](#primarylanguage) primaryLanguage: [LanguageInfo](https://docs.maptiler.com/sdk-js/api-reference/types/LanguageInfo/) = defaults.primaryLanguage The primary language. By default, the language of the web browser is used. ### `Optional` `Maptiler`secondaryLanguage[](#secondarylanguage) secondaryLanguage?: [LanguageInfo](https://docs.maptiler.com/sdk-js/api-reference/types/LanguageInfo/) The secondary language, to overwrite the default language defined in the map style. This settings is highly dependant on the style compatibility and may not work in most cases. ### `Maptiler`session[](#session) session: boolean = true Setting on whether of not the SDK runs with a session logic. A "session" is started at the initialization of the SDK and finished when the browser page is being closed or refreshed. When `session` is enabled (default: true), the extra URL param `mtsid` is added to queries to the MapTiler Cloud API. This allows MapTiler to enable "session based billing". ### `Maptiler`telemetry[](#telemetry) telemetry: boolean = true Telemetry is enabled by default but can be opted-out by setting this value to `false`. The telemetry is very valuable to the team at MapTiler because it shares information about where to add the extra effort. It also helps spotting some incompatibility issues that may arise between the SDK and a specific version of a module. It consists in sending metrics about usage of the following features: - SDK version \[string\] - API key \[string\] - MapTiler sesion ID (if opted-in) \[string\] - if tile caching is enabled \[boolean\] - if language specified at initialization \[boolean\] - if terrain is activated at initialization \[boolean\] - if globe projection is activated at initialization \[boolean\] In addition, each official module will be added to a list, alongside its version number. ## Accessors[](#accessors-1) ### `Maptiler`apiHost[](#apihost) - get apiHost(): string The host currently used for the MapTiler API requests (`api.maptiler.com` or `api.maptiler.eu`) #### Returns string ### `Maptiler`apiKey[](#apikey) - get apiKey(): string Get the MapTiler Cloud API key #### Returns string - set apiKey(k: string): void Set the MapTiler Cloud API key #### Parameters - k: string #### Returns void ### `Maptiler`apiURL[](#apiurl) - get apiURL(): string The base URL currently used for the MapTiler API requests (`https://api.maptiler.com/` or `https://api.maptiler.eu/`) #### Returns string ### `Maptiler`experimental\_defaultPathSampleSteps[](#experimental_defaultpathsamplesteps) - get experimental\_defaultPathSampleSteps(): number #### Returns number - set experimental\_defaultPathSampleSteps(s: number): void #### Parameters - s: number #### Returns void ### `Maptiler`experimental\_defaultWorkerCount[](#experimental_defaultworkercount) - get experimental\_defaultWorkerCount(): number #### Returns number - set experimental\_defaultWorkerCount(w: number): void #### Parameters - w: number #### Returns void ### `Maptiler`fetch[](#fetch) - get fetch(): [FetchFunction](https://docs.maptiler.com/sdk-js/api-reference/types/FetchFunction/) | null Get the fetch fucntion #### Returns [FetchFunction](https://docs.maptiler.com/sdk-js/api-reference/types/FetchFunction/) | null - set fetch(f: [FetchFunction](https://docs.maptiler.com/sdk-js/api-reference/types/FetchFunction/)): void Set a the custom fetch function to replace the default one #### Parameters - f: [FetchFunction](https://docs.maptiler.com/sdk-js/api-reference/types/FetchFunction/) #### Returns void ### `Maptiler`unit[](#unit) - get unit(): [Unit](https://docs.maptiler.com/sdk-js/api-reference/types/Unit/) Get the unit system #### Returns [Unit](https://docs.maptiler.com/sdk-js/api-reference/types/Unit/) - set unit(u: [Unit](https://docs.maptiler.com/sdk-js/api-reference/types/Unit/)): void Set the unit system #### Parameters - u: [Unit](https://docs.maptiler.com/sdk-js/api-reference/types/Unit/) #### Returns void ### `Maptiler`useEuEndpoints[](#useeuendpoints) - get useEuEndpoints(): boolean Whether the EU-based `api.maptiler.eu` host is currently in use instead of the default `api.maptiler.com` #### Returns boolean - set useEuEndpoints(value: boolean): void Switch between the default `api.maptiler.com` host and the EU-based `api.maptiler.eu` host. Set to `false` to switch back to the default. #### Parameters - value: boolean #### Returns void ## 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 Inherited from [EventEmitter](https://docs.maptiler.com/sdk-js/api-reference/classes/Externals.EventEmitter/).[\[captureRejectionSymbol\]](https://docs.maptiler.com/sdk-js/api-reference/classes/Externals.EventEmitter/#capturerejectionsymbol) ### addListener[](#addlistener) - addListener<[E](#addlistenere) extends string | symbol\>(     eventName: string | symbol,     listener: (...args: any\[\]) \=> void, ): this[](#addlistener-1) Alias for `emitter.on(eventName, listener)`. #### Type Parameters - E extends string | symbol #### Parameters - eventName: string | symbol - listener: (...args: any\[\]) \=> void #### Returns this #### Since[](#since-1) v0.1.26 Inherited from [EventEmitter](https://docs.maptiler.com/sdk-js/api-reference/classes/Externals.EventEmitter/).[addListener](https://docs.maptiler.com/sdk-js/api-reference/classes/Externals.EventEmitter/#addlistener) ### emit[](#emit) - emit<[E](#emite) extends string | symbol\>(     eventName: string | symbol,     ...args: 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: string | symbol - ...args: any\[\] #### Returns boolean #### Since[](#since-2) v0.1.26 Inherited from [EventEmitter](https://docs.maptiler.com/sdk-js/api-reference/classes/Externals.EventEmitter/).[emit](https://docs.maptiler.com/sdk-js/api-reference/classes/Externals.EventEmitter/#emit) ### 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 Inherited from [EventEmitter](https://docs.maptiler.com/sdk-js/api-reference/classes/Externals.EventEmitter/).[eventNames](https://docs.maptiler.com/sdk-js/api-reference/classes/Externals.EventEmitter/#eventnames) ### 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 Inherited from [EventEmitter](https://docs.maptiler.com/sdk-js/api-reference/classes/Externals.EventEmitter/).[getMaxListeners](https://docs.maptiler.com/sdk-js/api-reference/classes/Externals.EventEmitter/#getmaxlisteners) ### listenerCount[](#listenercount) - listenerCount<[E](#listenercounte) extends string | symbol\>(     eventName: string | symbol,     listener?: (...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: string | symbol The name of the event being listened for - `Optional`listener: (...args: any\[\]) \=> void The event handler function #### Returns number #### Since[](#since-5) v3.2.0 Inherited from [EventEmitter](https://docs.maptiler.com/sdk-js/api-reference/classes/Externals.EventEmitter/).[listenerCount](https://docs.maptiler.com/sdk-js/api-reference/classes/Externals.EventEmitter/#listenercount) ### listeners[](#listeners) - listeners<[E](#listenerse) extends string | symbol\>(     eventName: string | symbol, ): ((...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: string | symbol #### Returns ((...args: any\[\]) \=> void)\[\] #### Since[](#since-6) v0.1.26 Inherited from [EventEmitter](https://docs.maptiler.com/sdk-js/api-reference/classes/Externals.EventEmitter/).[listeners](https://docs.maptiler.com/sdk-js/api-reference/classes/Externals.EventEmitter/#listeners) ### off[](#off) - off<[E](#offe) extends string | symbol\>(     eventName: string | symbol,     listener: (...args: any\[\]) \=> void, ): this[](#off-1) Alias for `emitter.removeListener()`. #### Type Parameters - E extends string | symbol #### Parameters - eventName: string | symbol - listener: (...args: any\[\]) \=> void #### Returns this #### Since[](#since-7) v10.0.0 Inherited from [EventEmitter](https://docs.maptiler.com/sdk-js/api-reference/classes/Externals.EventEmitter/).[off](https://docs.maptiler.com/sdk-js/api-reference/classes/Externals.EventEmitter/#off) ### on[](#on) - on<[E](#one) extends string | symbol\>(     eventName: string | symbol,     listener: (...args: 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: string | symbol The name of the event. - listener: (...args: any\[\]) \=> void The callback function #### Returns this #### Since[](#since-8) v0.1.101 Inherited from [EventEmitter](https://docs.maptiler.com/sdk-js/api-reference/classes/Externals.EventEmitter/).[on](https://docs.maptiler.com/sdk-js/api-reference/classes/Externals.EventEmitter/#on) ### once[](#once) - once<[E](#oncee) extends string | symbol\>(     eventName: string | symbol,     listener: (...args: 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: string | symbol The name of the event. - listener: (...args: any\[\]) \=> void The callback function #### Returns this #### Since[](#since-9) v0.3.0 Inherited from [EventEmitter](https://docs.maptiler.com/sdk-js/api-reference/classes/Externals.EventEmitter/).[once](https://docs.maptiler.com/sdk-js/api-reference/classes/Externals.EventEmitter/#once) ### prependListener[](#prependlistener) - prependListener<[E](#prependlistenere) extends string | symbol\>(     eventName: string | symbol,     listener: (...args: 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: string | symbol The name of the event. - listener: (...args: any\[\]) \=> void The callback function #### Returns this #### Since[](#since-10) v6.0.0 Inherited from [EventEmitter](https://docs.maptiler.com/sdk-js/api-reference/classes/Externals.EventEmitter/).[prependListener](https://docs.maptiler.com/sdk-js/api-reference/classes/Externals.EventEmitter/#prependlistener) ### prependOnceListener[](#prependoncelistener) - prependOnceListener<[E](#prependoncelistenere) extends string | symbol\>(     eventName: string | symbol,     listener: (...args: 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: string | symbol The name of the event. - listener: (...args: any\[\]) \=> void The callback function #### Returns this #### Since[](#since-11) v6.0.0 Inherited from [EventEmitter](https://docs.maptiler.com/sdk-js/api-reference/classes/Externals.EventEmitter/).[prependOnceListener](https://docs.maptiler.com/sdk-js/api-reference/classes/Externals.EventEmitter/#prependoncelistener) ### rawListeners[](#rawlisteners) - rawListeners<[E](#rawlistenerse) extends string | symbol\>(     eventName: string | symbol, ): ((...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: string | symbol #### Returns ((...args: any\[\]) \=> void)\[\] #### Since[](#since-12) v9.4.0 Inherited from [EventEmitter](https://docs.maptiler.com/sdk-js/api-reference/classes/Externals.EventEmitter/).[rawListeners](https://docs.maptiler.com/sdk-js/api-reference/classes/Externals.EventEmitter/#rawlisteners) ### removeAllListeners[](#removealllisteners) - removeAllListeners<[E](#removealllistenerse) extends string | symbol\>(eventName?: 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: string | symbol #### Returns this #### Since[](#since-13) v0.1.26 Inherited from [EventEmitter](https://docs.maptiler.com/sdk-js/api-reference/classes/Externals.EventEmitter/).[removeAllListeners](https://docs.maptiler.com/sdk-js/api-reference/classes/Externals.EventEmitter/#removealllisteners) ### removeListener[](#removelistener) - removeListener<[E](#removelistenere) extends string | symbol\>(     eventName: string | symbol,     listener: (...args: 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: string | symbol - listener: (...args: any\[\]) \=> void #### Returns this #### Since[](#since-14) v0.1.26 Inherited from [EventEmitter](https://docs.maptiler.com/sdk-js/api-reference/classes/Externals.EventEmitter/).[removeListener](https://docs.maptiler.com/sdk-js/api-reference/classes/Externals.EventEmitter/#removelistener) ### 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 Inherited from [EventEmitter](https://docs.maptiler.com/sdk-js/api-reference/classes/Externals.EventEmitter/).[setMaxListeners](https://docs.maptiler.com/sdk-js/api-reference/classes/Externals.EventEmitter/#setmaxlisteners)