WorkerGlobalScope: fetch() method

Available in workers

The fetch() method of the 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 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 ok and/or 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 Request() constructor.

Syntax

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 stringifier — including a 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 baseURI in a window context, or location in a worker context.
    • A Request object.

• options Optional

  • : A RequestInit object containing any custom settings that you want to apply to the request.

Return value

A Promise that resolves to a Response object.

Exceptions

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

Examples

See fetch() for examples.

Specifications

Browser compatibility

See also

• fetch()
• Fetch API
• ServiceWorker API
• HTTP access control (CORS)
• HTTP