• Skip to main content
  • Select language
  • Skip to search
MDN Web Docs
  • Technologies
    • HTML
    • CSS
    • JavaScript
    • Graphics
    • HTTP
    • APIs / DOM
    • WebExtensions
    • MathML
  • References & Guides
    • Learn web development
    • Tutorials
    • References
    • Developer Guides
    • Accessibility
    • Game development
    • ...more docs
Add-ons
  1. MDN
  2. Mozilla
  3. Add-ons
  4. Browser extensions
  5. JavaScript APIs
  6. webRequest
  7. webRequest.BlockingResponse

webRequest.BlockingResponse

In This Article
  1. Type
  2. Browser compatibility

An object of this type is returned by event listeners that have set "blocking" in their extraInfoSpec argument.

By setting particular properties in BlockingResponse, the listener can modify network requests.

Note that you can't set all this object's properties in every listener: the properties you can set are dependent on the event that triggered this listener, as detailed below.

Type

Values of this type are objects. They contain the following properties:

cancelOptional
boolean. If true, the request is cancelled. You can only set this property in onBeforeRequest, onBeforeSendHeaders, and onAuthRequired.
redirectUrlOptional
string. This is a URL, and if set, the original request is redirected to that URL. You can only set this property in onBeforeRequest or onHeadersReceived.
Redirections to non-HTTP schemes such as data: are allowed, but they are not currently supported (bug 707624). Redirects use the same request method as the original request unless initiated from onHeadersReceived stage, in which case the redirect uses the GET method.
requestHeadersOptional

webRequest.HttpHeaders. This is an HttpHeaders object, an array in which each object represents a header. If set, the request is made with these headers rather than the original headers. You can only set this property in onBeforeSendHeaders .

responseHeadersOptional
webRequest.HttpHeaders. This is an HttpHeaders object, an array in which each object represents a header. If set, the server is assumed to have responded with these response headers instead of the originals. You can only set this property in onHeadersReceived.
authCredentialsOptional
object. If set, the request is made using the given credentials. You can only set this property in onAuthRequired. The authCredentials property is an object with the following properties:
username
string. Username to supply.
password
string. Password to supply.

Browser compatibility

The compatibility table in this page is generated from structured data. If you'd like to contribute to the data, please check out https://github.com/mdn/browser-compat-data and send us a pull request.

ChromeEdgeFirefoxFirefox for AndroidOpera
Basic supportYesYes4548Yes

Acknowledgements

This API is based on Chromium's chrome.webRequest API. This documentation is derived from web_request.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.

// Copyright 2015 The Chromium Authors. All rights reserved.
//
// Redistribution and use in source and binary forms, with or without
// modification, are permitted provided that the following conditions are
// met:
//
//    * Redistributions of source code must retain the above copyright
// notice, this list of conditions and the following disclaimer.
//    * Redistributions in binary form must reproduce the above
// copyright notice, this list of conditions and the following disclaimer
// in the documentation and/or other materials provided with the
// distribution.
//    * Neither the name of Google Inc. nor the names of its
// contributors may be used to endorse or promote products derived from
// this software without specific prior written permission.
//
// THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
// "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
// LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
// A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
// OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
// SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
// LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
// DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
// THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
// (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
// OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.

Document Tags and Contributors

Tags: 
  • Add-ons
  • API
  • BlockingResponse
  • Extensions
  • Non-standard
  • Reference
  • Type
  • WebExtensions
  • webRequest
 Contributors to this page: socram8888, wbamberg, rolfedh
 Last updated by: socram8888, Oct 21, 2016, 5:46:36 PM
See also
  1. Browser extensions
  2. Getting started
    1. What are extensions?
    2. Your first extension
    3. Your second extension
    4. Anatomy of an extension
    5. Example extensions
  3. How to
    1. Intercept HTTP requests
    2. Modify a web page
    3. Add a button to the toolbar
    4. Implement a settings page
  4. User interface
    1. Introduction
    2. Toolbar button
    3. Address bar button
    4. Sidebar
    5. Context menu items
    6. Options page
    7. Bundled web pages
    8. Notifications
    9. Address bar suggestions
    10. Developer tools panels
  5. Concepts
    1. Using the JavaScript APIs
    2. Content scripts
    3. Match patterns
    4. Internationalization
    5. Content Security Policy
    6. Native messaging
  6. Porting
    1. Porting a Google Chrome extension
    2. Porting a legacy Firefox extension
    3. Embedded WebExtensions
    4. Comparison with the Add-on SDK
    5. Comparison with XUL/XPCOM extensions
    6. Chrome incompatibilities
    7. Differences between desktop and Android
  7. Firefox workflow
    1. Temporary Installation in Firefox
    2. Debugging
    3. Developing for Firefox for Android
    4. Getting started with web-ext
    5. web-ext command reference
    6. Extensions and the Add-on ID
    7. Publishing your extension
  8. JavaScript APIs
    1. Browser support for JavaScript APIs
    2. alarms
    3. bookmarks
    4. browserAction
    5. browsingData
    6. commands
    7. contextMenus
    8. contextualIdentities
    9. cookies
    10. devtools.inspectedWindow
    11. devtools.network
    12. devtools.panels
    13. downloads
    14. events
    15. extension
    16. extensionTypes
    17. history
    18. i18n
    19. identity
    20. idle
    21. management
    22. notifications
    23. omnibox
    24. pageAction
    25. permissions
    26. privacy
    27. proxy
    28. runtime
    29. sessions
    30. sidebarAction
    31. storage
    32. tabs
    33. topSites
    34. types
    35. webNavigation
    36. webRequest
      1. Methods
        1. handlerBehaviorChanged()
      2. Properties
        1. MAX_HANDLER_BEHAVIOR_CHANGED_CALLS_PER_10_MINUTES
      3. Types
        1. BlockingResponse
        2. HttpHeaders
        3. RequestFilter
        4. ResourceType
        5. UploadData
      4. Events
        1. onAuthRequired
        2. onBeforeRedirect
        3. onBeforeRequest
        4. onBeforeSendHeaders
        5. onCompleted
        6. onErrorOccurred
        7. onHeadersReceived
        8. onResponseStarted
        9. onSendHeaders
    37. windows
  9. Manifest keys
    1. applications
    2. author
    3. background
    4. browser_action
    5. chrome_settings_overrides
    6. chrome_url_overrides
    7. commands
    8. content_scripts
    9. content_security_policy
    10. default_locale
    11. description
    12. developer
    13. devtools_page
    14. homepage_url
    15. icons
    16. incognito
    17. manifest_version
    18. name
    19. omnibox
    20. optional_permissions
    21. options_ui
    22. page_action
    23. permissions
    24. protocol_handlers
    25. short_name
    26. sidebar_action
    27. version
    28. web_accessible_resources
  10. Themes
  11. Publishing add-ons
  12. Guides
    1. Signing and distribution overview
    2. Submit an add-on
    3. Creating an appealing listing
    4. Review policies
    5. Developer agreement
    6. Featured add-ons
    7. Contact addons.mozilla.org
  13. Community and support
  14. Channels
    1. Add-ons blog
    2. Add-on forums
    3. Stack Overflow
    4. Development newsgroup
    5. IRC Channel
  15. Legacy add-ons
  16. Legacy technologies
    1. Add-on SDK
    2. Legacy Firefox for Android
    3. Bootstrapped extensions
    4. Overlay extensions