1. Web
  2. Web APIs
  3. NavigationPreloadManager
  4. getState()

NavigationPreloadManager: getState() method

Baseline Widely available

This feature is well established and works across many devices and browser versions. It’s been available across browsers since ⁨April 2022⁩.

Secure context: This feature is available only in secure contexts (HTTPS), in some or all supporting browsers.

Note: This feature is available in Web Workers.

The getState() method of the NavigationPreloadManager interface returns a Promise that resolves to an object with properties that indicate whether preload is enabled and what value will be sent in the Service-Worker-Navigation-Preload HTTP header.

Syntax

js
getState()

Parameters

None.

Return value

A Promise that resolves with an object that has the following properties:

enabled

true if preloading is enabled, and false otherwise.

headerValue

A string containing the value that will be sent in the Service-Worker-Navigation-Preload HTTP header following a preloading fetch(). This defaults to true unless the value was changed using NavigationPreloadManager.setHeaderValue().

Exceptions

InvalidStateError DOMException

There is no active worker associated with the registration to which this NavigationPreloadManager belongs.

Examples

The code below shows a request for the current state, made once the service worker is ready.

js
navigator.serviceWorker.ready
  .then((registration) => registration.navigationPreload.getState())
  .then((state) => {
    console.log(state.enabled); // boolean
    console.log(state.headerValue); // string
  })
  .catch((e) =>
    console.error(`NavigationPreloadManager not supported: ${e.message}`),
  );

Specifications

Specification
Service Workers
# dom-navigationpreloadmanager-getstate

Browser compatibility

Help improve MDN

Learn how to contribute

This page was last modified on by MDN contributors.

View this page on GitHub • Report a problem with this content