Utilities related to your extension. Get URLs to resources packages with your extension, get the Window object for your extension's pages, get the values for various settings. Note that the messaging APIs in this module are deprecated in favor of the equivalent APIs in the runtime module.


The type of extension view.


Set for the lifetime of a callback if an ansychronous extension api has resulted in an error. If no error has occured lastError will be undefined.
True for content scripts running inside incognito tabs, and for extension pages running inside an incognito process. The latter only applies to extensions with 'split' incognito_behavior.


Returns the Window object for the background page running inside the current extension. Returns null if the extension has no background page.
Returns an array of the JavaScript Window objects for each of the tabs running inside the current extension.
Converts a relative path within an extension install directory to a fully-qualified URL.
Returns an array of the Window objects for each of the pages running inside the current extension.
Retrieves the state of the extension's access to Incognito-mode (as determined by the user-controlled 'Allowed in Incognito' checkbox).
Retrieves the state of the extension's access to the 'file://' scheme (as determined by the user-controlled 'Allow access to File URLs' checkbox).
Sets the value of the ap CGI parameter used in the extension's update URL. This value is ignored for extensions that are hosted in the browser vendor's store.


Fired when a request is sent from either an extension process or a content script.
Fired when a request is sent from another extension.
Sends a single request to other listeners within the extension.

Browser compatibility

ChromeEdgeFirefoxFirefox for AndroidOpera
ViewType Yes No4548 Yes
getBackgroundPage Yes144548 Yes
getExtensionTabs Yes No No No No
getURL Yes144548 Yes
getViews Yes1445 *48 * Yes
inIncognitoContext Yes174548 Yes
isAllowedFileSchemeAccess Yes No4848 Yes
isAllowedIncognitoAccess Yes174848 Yes
lastError Yes No4748 Yes
onRequest Yes No No No Yes
onRequestExternal Yes No No No Yes
sendRequest Yes No No No No
setUpdateUrlData Yes No No No Yes

Example extensions


This API is based on Chromium's chrome.extension API. This documentation is derived from extension.json in the Chromium code.

Microsoft Edge compatibility data is supplied by Microsoft Corporation and is included here under the Creative Commons Attribution 3.0 United States License.

Document Tags and Contributors

Contributors to this page: hellosct1, wbamberg, andrewtruongmoz, abbycar, bsilverberg
Last updated by: hellosct1,