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WorkerGlobalScope: fetch() method

files/en-us/web/api/workerglobalscope/fetch/index.md

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{{APIRef("Fetch API")}}{{AvailableInWorkers("worker")}}

The fetch() method of the {{domxref("WorkerGlobalScope")}} interface starts the process of fetching a resource from the network, returning a promise that is fulfilled once the response is available.

The promise resolves to the {{domxref("Response")}} object representing the response to your request.

A fetch() promise only rejects when the request fails, for example, because of a badly-formed request URL or a network error. A fetch() promise does not reject if the server responds with HTTP status codes that indicate errors (404, 504, etc.). Instead, a then() handler must check the {{domxref("Response.ok")}} and/or {{domxref("Response.status")}} properties.

The fetch() method is controlled by the connect-src directive of Content Security Policy rather than the directive of the resources it's retrieving.

[!NOTE] The fetch() method's parameters are identical to those of the {{domxref("Request.Request","Request()")}} constructor.

Syntax

js-nolint
fetch(resource)
fetch(resource, options)

Parameters

  • resource

    • : This defines the resource that you wish to fetch. This can either be:
      • A string or any other object with a {{Glossary("stringifier")}} — including a {{domxref("URL")}} object — that provides the URL of the resource you want to fetch. The URL may be relative to the base URL, which is the document's {{domxref("Node.baseURI", "baseURI")}} in a window context, or {{domxref("WorkerGlobalScope.location")}} in a worker context.
      • A {{domxref("Request")}} object.

  • options {{optional_inline}}

    • : A {{domxref("RequestInit")}} object containing any custom settings that you want to apply to the request.

Return value

A {{jsxref("Promise")}} that resolves to a {{domxref("Response")}} object.

Exceptions

  • AbortError {{domxref("DOMException")}}
    • : The request was aborted due to a call to the {{domxref("AbortController")}} {{domxref("AbortController.abort", "abort()")}} method.
  • NotAllowedError {{domxref("DOMException")}}
    • : Thrown if use of the Topics API is specifically disallowed by a {{httpheader('Permissions-Policy/browsing-topics','browsing-topics')}} Permissions Policy, and a fetch() request was made with browsingTopics: true.
  • {{jsxref("TypeError")}}
    • : An error when the fetch operation could not be performed. See {{domxref("Window.fetch()")}} exceptions for a list of reasons why this error can occur.

Examples

See {{domxref("Window.fetch", "fetch()")}} for examples.

Specifications

{{Specifications}}

Browser compatibility

{{Compat}}

See also