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Add-ons
  1. MDN
  2. Mozilla
  3. Add-ons
  4. Browser extensions
  5. JavaScript APIs
  6. runtime
  7. runtime.sendMessage()

runtime.sendMessage()

In This Article
  1. Syntax
    1. Parameters
    2. Return value
  2. Browser compatibility
  3. Examples
    1. Example extensions

Sends a single message to event listeners within your extension or a different extension.

If sending to your extension, omit the extensionId argument. The runtime.onMessage event will be fired in each page in your extension, except for the frame that called runtime.sendMessage.

If sending to a different extension, include the extensionId argument set to the other extension's ID. runtime.onMessageExternal will be fired in the other extension.

Extensions cannot send messages to content scripts using this method. To send messages to content scripts, use tabs.sendMessage.

This is an asynchronous function that returns a Promise.

Syntax

var sending = browser.runtime.sendMessage(
  extensionId,             // optional string
  message,                 // any
  options                  // optional object
)

Parameters

extensionIdOptional
string. The ID of the extension to send the message to. Include this to send the message to a different extension. If the intended recipient has set an ID explicitly using the applications key in manifest.json, then extensionId should have this value. Otherwise it should be have the ID that was generated for the intended recipient.
If extensionId is omitted, the message will be sent to your own extension.
message
any. An object that can be serialized to JSON.
optionsOptional
object.
includeTlsChannelIdOptional
boolean. Whether the TLS channel ID will be passed into runtime.onMessageExternal for processes that are listening for the connection event.
toProxyScriptOptional
boolean. Must be True if the message is intended for a PAC file loaded using the proxy API.

Depending on the arguments it is given, this API is sometimes ambiguous. The following rules are used:

  • if one argument is given, it is the message to send, and the message will be sent internally.
  • if two arguments are given:
    • the arguments are interpreted as (message, options), and the message is sent internally, if the second argument is any of the following:
      1. a valid options object (meaning, it is an object which contains only the properties of options that the browser supports)
      2. null
      3. undefined
    • otherwise, the arguments are interpreted as (extensionId, message). The message will be sent to the extension identified by extensionId.
  • if three arguments are given, the arguments are interpreted as (extensionId, message, options). The message will be sent to the extension identified by extensionId.

Note that before Firefox 55, the rules were different in the 2-argument case. Under the old rules, if the first argument was a string, it was treated as the extensionId, with the message as the second argument. This meant that if you called sendMessage() with arguments like ("my-message", {}), then it would send an empty message to the extension identified by "my-message". Under the new rules, with these arguments you would send the message "my-message" internally, with an empty options object.

Return value

A Promise. If the receiver sent a response, this will be fulfilled with the response as a JSON object. Otherwise it will be fulfilled with no arguments. If an error occurs while connecting to the extension, the promise will be rejected with an error message.

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 support26Yes 1454815
options.includeTlsChannelId32No454819
options.toProxyScriptNoNo5555No
1. `runtime.onMessage` listeners in extension views receive the messages they sent.

Examples

Here's a content script that sends a message to the background script when the user clicks the content window. The message payload is {greeting: "Greeting from the content script"}, and the sender also expects to get a response, which is handled in the handleResponse function:

// content-script.js
function handleResponse(message) {
  console.log(`Message from the background script:  ${message.response}`);
}
function handleError(error) {
  console.log(`Error: ${error}`);
}
function notifyBackgroundPage(e) {
  var sending = browser.runtime.sendMessage({
    greeting: "Greeting from the content script"
  });
  sending.then(handleResponse, handleError);  
}
window.addEventListener("click", notifyBackgroundPage);

The corresponding background script looks like this:

// background-script.js
function handleMessage(request, sender, sendResponse) {
  console.log("Message from the content script: " +
    request.greeting);
  sendResponse({response: "Response from background script"});
}
browser.runtime.onMessage.addListener(handleMessage);

Example extensions

  • embedded-webextension-bootstrapped
  • embedded-webextension-sdk
  • mocha-client-tests
  • notify-link-clicks-i18n
  • proxy-blocker
  • webpack-modules

Acknowledgements

This API is based on Chromium's chrome.runtime API. This documentation is derived from runtime.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
  • Extensions
  • Method
  • Non-standard
  • Reference
  • runtime
  • sendMessage
  • WebExtensions
 Contributors to this page: jonathanKingston, andrewtruongmoz, wbamberg, Rob W, jsnjack, Makyen, chrisdavidmills
 Last updated by: jonathanKingston, Jul 19, 2017, 7:08:06 AM
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
      1. Methods
        1. connect()
        2. connectNative()
        3. getBackgroundPage()
        4. getManifest()
        5. getPackageDirectoryEntry()
        6. getPlatformInfo()
        7. getURL()
        8. openOptionsPage()
        9. reload()
        10. requestUpdateCheck()
        11. sendMessage()
        12. sendNativeMessage()
        13. setUninstallURL()
      2. Properties
        1. id
        2. lastError
      3. Types
        1. MessageSender
        2. OnInstalledReason
        3. OnRestartRequiredReason
        4. PlatformArch
        5. PlatformInfo
        6. PlatformNaclArch
        7. PlatformOs
        8. Port
        9. RequestUpdateCheckStatus
      4. Events
        1. onBrowserUpdateAvailable
        2. onConnect
        3. onConnectExternal
        4. onInstalled
        5. onMessage
        6. onMessageExternal
        7. onRestartRequired
        8. onStartup
        9. onSuspend
        10. onSuspendCanceled
        11. onUpdateAvailable
    29. sessions
    30. sidebarAction
    31. storage
    32. tabs
    33. topSites
    34. types
    35. webNavigation
    36. webRequest
    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