---
title: "EventEmitterReferencingAsyncResource | 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 EventEmitterReferencingAsyncResource

The class `AsyncResource` is designed to be extended by the embedder's async resources. Using this, users can easily trigger the lifetime events of their own resources.

The `init` hook will trigger when an `AsyncResource` is instantiated.

The following is an overview of the `AsyncResource` API.

```typescript
import { AsyncResource, executionAsyncId } from 'node:async_hooks';

// AsyncResource() is meant to be extended. Instantiating a
// new AsyncResource() also triggers init. If triggerAsyncId is omitted then
// async_hook.executionAsyncId() is used.
const asyncResource = new AsyncResource(
  type, { triggerAsyncId: executionAsyncId(), requireManualDestroy: false },
);

// Run a function in the execution context of the resource. This will
// * establish the context of the resource
// * trigger the AsyncHooks before callbacks
// * call the provided function `fn` with the supplied arguments
// * trigger the AsyncHooks after callbacks
// * restore the original execution context
asyncResource.runInAsyncScope(fn, thisArg, ...args);

// Call AsyncHooks destroy callbacks.
asyncResource.emitDestroy();

// Return the unique ID assigned to the AsyncResource instance.
asyncResource.asyncId();

// Return the trigger ID for the AsyncResource instance.
asyncResource.triggerAsyncId();
```

interface EventEmitterReferencingAsyncResource {  
    [eventEmitter](#eventemitter): [EventEmitterAsyncResource](https://docs.maptiler.com/sdk-js/api-reference/classes/Externals.EventEmitter.EventEmitterAsyncResource/);  
    [asyncId](#asyncid-1)(): number;  
    [bind](#bind-1)<[Func](#bindfunc) extends (...args: any\[\]) \=> any\>(fn: [Func](#bindfunc)): [Func](#bindfunc);  
    [emitDestroy](#emitdestroy-1)(): this;  
    [runInAsyncScope](#runinasyncscope-1)<[This](#runinasyncscopethis), [Result](#runinasyncscoperesult)\>(  
        fn: (this: [This](#runinasyncscopethis), ...args: any\[\]) \=> [Result](#runinasyncscoperesult),  
        thisArg?: [This](#runinasyncscopethis),  
        ...args: any\[\],  
    ): [Result](#runinasyncscoperesult);  
    [triggerAsyncId](#triggerasyncid-1)(): number;  
}

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

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

##### Index

### Properties[](#properties)

[eventEmitter](#eventemitter)

### Methods[](#methods)

[asyncId](#asyncid) [bind](#bind) [emitDestroy](#emitdestroy) [runInAsyncScope](#runinasyncscope) [triggerAsyncId](#triggerasyncid)

## Properties[](#properties-1)

### `Readonly`eventEmitter[](#eventemitter)

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

## Methods[](#methods-1)

### asyncId[](#asyncid)

-   asyncId(): number[](#asyncid-1)
    
    #### Returns number
    
    The unique `asyncId` assigned to the resource.
    
    Inherited from [AsyncResource](https://docs.maptiler.com/sdk-js/api-reference/classes/Externals.AsyncResource/).[asyncId](https://docs.maptiler.com/sdk-js/api-reference/classes/Externals.AsyncResource/#asyncid)
    

### bind[](#bind)

-   bind<[Func](#bindfunc) extends (...args: any\[\]) \=> any\>(fn: [Func](#bindfunc)): [Func](#bindfunc)[](#bind-1)
    
    Binds the given function to execute to this `AsyncResource`'s scope.
    
    #### Type Parameters
    
    -   Func extends (...args: any\[\]) \=> any
    
    #### Parameters
    
    -   fn: [Func](#bindfunc)
        
        The function to bind to the current `AsyncResource`.
        
    
    #### Returns [Func](#bindfunc)
    
    #### Since[](#since)
    
    v14.8.0, v12.19.0
    
    Inherited from [AsyncResource](https://docs.maptiler.com/sdk-js/api-reference/classes/Externals.AsyncResource/).[bind](https://docs.maptiler.com/sdk-js/api-reference/classes/Externals.AsyncResource/#bind)
    

### emitDestroy[](#emitdestroy)

-   emitDestroy(): this[](#emitdestroy-1)
    
    Call all `destroy` hooks. This should only ever be called once. An error will be thrown if it is called more than once. This **must** be manually called. If the resource is left to be collected by the GC then the `destroy` hooks will never be called.
    
    #### Returns this
    
    A reference to `asyncResource`.
    
    Inherited from [AsyncResource](https://docs.maptiler.com/sdk-js/api-reference/classes/Externals.AsyncResource/).[emitDestroy](https://docs.maptiler.com/sdk-js/api-reference/classes/Externals.AsyncResource/#emitdestroy)
    

### runInAsyncScope[](#runinasyncscope)

-   runInAsyncScope<[This](#runinasyncscopethis), [Result](#runinasyncscoperesult)\>(  
        fn: (this: [This](#runinasyncscopethis), ...args: any\[\]) \=> [Result](#runinasyncscoperesult),  
        thisArg?: [This](#runinasyncscopethis),  
        ...args: any\[\],  
    ): [Result](#runinasyncscoperesult)[](#runinasyncscope-1)
    
    Call the provided function with the provided arguments in the execution context of the async resource. This will establish the context, trigger the AsyncHooks before callbacks, call the function, trigger the AsyncHooks after callbacks, and then restore the original execution context.
    
    #### Type Parameters
    
    -   This
    -   Result
    
    #### Parameters
    
    -   fn: (this: [This](#runinasyncscopethis), ...args: any\[\]) \=> [Result](#runinasyncscoperesult)
        
        The function to call in the execution context of this async resource.
        
    -   `Optional`thisArg: [This](#runinasyncscopethis)
        
        The receiver to be used for the function call.
        
    -   ...args: any\[\]
        
        Optional arguments to pass to the function.
        
    
    #### Returns [Result](#runinasyncscoperesult)
    
    #### Since[](#since-1)
    
    v9.6.0
    
    Inherited from [AsyncResource](https://docs.maptiler.com/sdk-js/api-reference/classes/Externals.AsyncResource/).[runInAsyncScope](https://docs.maptiler.com/sdk-js/api-reference/classes/Externals.AsyncResource/#runinasyncscope)
    

### triggerAsyncId[](#triggerasyncid)

-   triggerAsyncId(): number[](#triggerasyncid-1)
    
    #### Returns number
    
    The same `triggerAsyncId` that is passed to the `AsyncResource` constructor.
    
    Inherited from [AsyncResource](https://docs.maptiler.com/sdk-js/api-reference/classes/Externals.AsyncResource/).[triggerAsyncId](https://docs.maptiler.com/sdk-js/api-reference/classes/Externals.AsyncResource/#triggerasyncid)