runtime.onMessage

Fired when a message is received from either an extension process or a content script.

Syntax

chrome.runtime.onMessage.addListener(function(
  message,         // optional any
  sender,          // MessageSender
  function() {...} // function
) {...})
chrome.runtime.onMessage.removeListener(listener)
chrome.runtime.onMessage.hasListener(listener)

This API is also available as browser.runtime.onMessage.*.

Events have three functions:

addListener(callback)

Adds a listener to this event.

removeListener(listener)

Stop listening to this event. The listener argument is the listener to remove.

hasListener(listener)

Checks whether a listener is registered for this event. Returns true if it is listening, false otherwise.

addListener syntax

Parameters

function

A callback function that will be called when this event occurs. The function will be passed the following arguments:

message

any. The message sent by the calling script.

sender

A runtime.MessageSender object representing the sender of the message.

sendResponse

A function to call (at most once) to handle sending a response to the message. The argument should be any JSON-ifiable object. If you have more than one onMessage listener in the same document, then only one may send a response. This function becomes invalid when the event listener returns, unless you return true from the event listener to indicate you wish to send a response asynchronously (this will keep the message channel open to the other end until sendResponse is called).

This function returns a boolean. It should return true from the event listener if you wish to call sendResponse after the event listener returns.

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.

Compatibility notes

Edge

• 'MessageSender.tlsChannelId' is not supported.

Examples

This content script listens for click events in the web page. If the click was on a link, it messages the background page with the target URL:

// content-script.js

window.addEventListener("click", notifyExtension);

function notifyExtension(e) {
  if (e.target.tagName != "A") {
    return;
  }
  chrome.runtime.sendMessage({"url": e.target.href});

The background script listens for these messages and displays a notification using the notifications API:

// background-script.js

chrome.runtime.onMessage.addListener(notify);

function notify(message) {
  chrome.notifications.create({
    "type": "basic",
    "iconUrl": chrome.extension.getURL("link.png"),
    "title": "You clicked a link!",
    "message": message.url
  });
}

Example add-ons

• beastify
• cookie-bg-picker
• notify-link-clicks-i18n

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