tabs.sendMessage()

Sends a single message from the extension's background scripts (or other privileged scripts, such as popup scripts or options page scripts) to any content scripts that belong to the extension and are running in the specified tab.

The message will be received in the content scripts by any listeners to the runtime.onMessage event. Listeners may then optionally send a response back to the background script using the sendResponse argument.

This is an asynchronous function that returns a Promise.

SyntaxEdit

var sending = browser.tabs.sendMessage(
  tabId,                   // integer
  message,                 // any
  options                  // optional object
)

Parameters

tabId

integer. ID of the tab whose content scripts we want to send a message to.

message

any. An object that can be serialized to JSON.

optionsOptional

object.

frameIdOptional

integer. Sends the message to a specific frame identified by frameId instead of all frames in the tab.

Return value

A Promise that will be fulfilled with the JSON response object sent by the handler of the message in the content script, or with no arguments if the content script did not send a response. If an error occurs while connecting to the specified tab or any other error occurs, the promise will be rejected with an error message.

Browser compatibilityEdit

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.

ExamplesEdit

Here's an example of a background script that sends a message to the content scripts running in the active tab when the user clicks the browser action. The background script also expect the content script to send a response:

// background-script.js
"use strict";

function onError(error) {
  console.error(`Error: ${error}`);
}

function sendMessageToTabs(tabs) {
  for (let tab of tabs) {
    browser.tabs.sendMessage(
      tab.id,
      {greeting: "Hi from background script"}
    ).then(response => {
      console.log("Message from the content script:");
      console.log(response.response);
    }).catch(onError);
  }
}

browser.browserAction.onClicked.addListener(() => {
  browser.tabs.query({
    currentWindow: true,
    active: true
  }).then(sendMessageToTabs).catch(onError);
});

Here's the corresponding content script:

// content-script.js
"use strict";

browser.runtime.onMessage.addListener(request => {
  console.log("Message from the background script:");
  console.log(request.greeting);
  return Promise.resolve({response: "Hi from content script"});
});

Example extensions

• beastify
• cookie-bg-picker
• imagify

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