---
title: "RequestTransformFunction | 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.

# Type Alias RequestTransformFunction

RequestTransformFunction: (  
    url: string,  
    resourceType?: [ResourceType](https://docs.maptiler.com/sdk-js/api-reference/enums/ResourceType/),  
) \=> [RequestParameters](https://docs.maptiler.com/sdk-js/api-reference/types/RequestParameters/) | Promise<[RequestParameters](https://docs.maptiler.com/sdk-js/api-reference/types/RequestParameters/)\> | undefined

This function is used to transform a request. It is used just before executing the relevant request.

#### Type Declaration

-   -   (  
            url: string,  
            resourceType?: [ResourceType](https://docs.maptiler.com/sdk-js/api-reference/enums/ResourceType/),  
        ): [RequestParameters](https://docs.maptiler.com/sdk-js/api-reference/types/RequestParameters/) | Promise<[RequestParameters](https://docs.maptiler.com/sdk-js/api-reference/types/RequestParameters/)\> | undefined
    -   #### Parameters
        
        -   url: string
        -   `Optional`resourceType: [ResourceType](https://docs.maptiler.com/sdk-js/api-reference/enums/ResourceType/)
        
        #### Returns [RequestParameters](https://docs.maptiler.com/sdk-js/api-reference/types/RequestParameters/) | Promise<[RequestParameters](https://docs.maptiler.com/sdk-js/api-reference/types/RequestParameters/)\> | undefined