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 or extension pages/iframes that belong to the extension and are running in the specified tab.
The message will be received in the extension context by any listeners to the runtime.onMessage
event. Listeners may then optionally return something as a response back to the sender.
This is an asynchronous function that returns a Promise
.
Note: You can also use a connection-based approach to exchange messages.
Syntax
const 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 (see Data cloning algorithm). options
Optional-
object
.frameId
Optional-
integer
. Sends the message to a specific frame identified byframeId
instead of all frames in the tab. Whether the content script is executed in all frames depends on theall_frames
setting in thecontent_scripts
section ofmanifest.json
.
Return value
A Promise
that will be fulfilled with the 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.
If several frames respond to the message, the promise is resolved to one of answers.
Examples
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 expects the content script to send a response:
// background-script.js
"use strict";
function onError(error) {
console.error(`Error: ${error}`);
}
function sendMessageToTabs(tabs) {
for (const 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
Browser compatibility
BCD tables only load in the browser
Note: This API is based on Chromium's chrome.tabs
API. This documentation is derived from tabs.json
in the Chromium code.