---
title: Fetch Handler
description: Handle incoming HTTP requests in Cloudflare Workers using the fetch() handler and return responses.
image: https://developers.cloudflare.com/dev-products-preview.png
---

> Documentation Index  
> Fetch the complete documentation index at: https://developers.cloudflare.com/workers/llms.txt  
> Use this file to discover all available pages before exploring further.

[Skip to content](#%5Ftop) 

# Fetch Handler

## Background

Incoming HTTP requests to a Worker are passed to the `fetch()` handler as a [Request](https://developers.cloudflare.com/workers/runtime-apis/request/) object. To respond to the request with a response, return a [Response](https://developers.cloudflare.com/workers/runtime-apis/response/) object:

JavaScript

```

export default {

  async fetch(request, env, ctx) {

    return new Response('Hello World!');

  },

};


```

Note

The Workers runtime does not support `XMLHttpRequest` (XHR). Learn the difference between `XMLHttpRequest` and `fetch()` in the [MDN ↗](https://developer.mozilla.org/en-US/docs/Web/API/XMLHttpRequest) documentation.

### Parameters

* `request` Request  
   * The incoming HTTP request.
* `env` object  
   * The [bindings](https://developers.cloudflare.com/workers/runtime-apis/bindings/) available to the Worker. As long as the [environment](https://developers.cloudflare.com/workers/wrangler/environments/) has not changed, the same object (equal by identity) may be passed to multiple requests. You can also [import env from cloudflare:workers](https://developers.cloudflare.com/workers/runtime-apis/bindings/#importing-env-as-a-global) to access bindings from anywhere in your code.
* `ctx.waitUntil(promisePromise)` : void  
   * Refer to [waitUntil](https://developers.cloudflare.com/workers/runtime-apis/context/#waituntil).
* `ctx.passThroughOnException()` : void  
   * Refer to [passThroughOnException](https://developers.cloudflare.com/workers/runtime-apis/context/#passthroughonexception).

```json
{"@context":"https://schema.org","@type":"BreadcrumbList","itemListElement":[{"@type":"ListItem","position":1,"item":{"@id":"/directory/","name":"Directory"}},{"@type":"ListItem","position":2,"item":{"@id":"/workers/","name":"Workers"}},{"@type":"ListItem","position":3,"item":{"@id":"/workers/runtime-apis/","name":"Runtime APIs"}},{"@type":"ListItem","position":4,"item":{"@id":"/workers/runtime-apis/handlers/","name":"Handlers"}},{"@type":"ListItem","position":5,"item":{"@id":"/workers/runtime-apis/handlers/fetch/","name":"Fetch Handler"}}]}
```