Call this function to set up a connection between the extension's background scripts (or other privileged scripts, such as popup scripts or options page scripts) and any content scripts that belong to this extension and are running in the specified tab. This function returns a runtime.Port object.

When this is called, the runtime.onConnect event will be fired in any content script belonging to this extension that are running in the specified tab. The event listener will be passed another runtime.Port object. The two sides can then use the Port objects to exchange messages.

For more details, see connection-based messaging. You can message without creating a connection, for advice on choosing between the options, see Choosing between one-off messages and connection-based messaging.


  tabId,      // integer
  connectInfo // optional object



integer. ID of the tab whose content scripts we want to connect to.

connectInfo Optional

An object with the following properties:

name Optional

string. Will be passed into runtime.onConnect event listeners in content scripts belonging to this extension and running in the specified tab.

frameId Optional

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

Return value

runtime.Port. A port that can be used to communicate with the content scripts running in the specified tab.


In this example a background script listens for a click on a browser action, then connects to the currently active tab, then sends a message using the Port that's returned from connect():

function connectToTab(tabs) {
  if (tabs.length > 0) {
    let examplePort = browser.tabs.connect(tabs[0].id, {
      name: "tabs-connect-example",
    examplePort.postMessage({ greeting: "Hi from background script" });

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

browser.browserAction.onClicked.addListener(() => {
  let gettingActive = browser.tabs.query({
    currentWindow: true,
    active: true,
  gettingActive.then(connectToTab, onError);

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.