runtime.onConnectExternal
Fired when an extension receives a connection request from a different extension.
To send a message which will be received by the onConnectExternal listener, use runtime.connect(), passing the ID of the recipient in the extensionId parameter.
The listener is passed a runtime.Port object which it can then use to send and receive messages. The Port object also contains a sender property, which is a runtime.MessageSender object, and which the recipient can use to check the sender's ID.
Syntax
browser.runtime.onConnectExternal.addListener(listener) browser.runtime.onConnectExternal.removeListener(listener) browser.runtime.onConnectExternal.hasListener(listener) Events have three functions:
addListener(listener)-
Adds a listener to this event.
removeListener(listener)-
Stop listening to this event. The
listenerargument is the listener to remove. hasListener(listener)-
Checks whether a
listeneris registered for this event. Returnstrueif it is listening,falseotherwise.
addListener syntax
Parameters
function-
The function called when this event occurs. The function is passed this argument:
port-
A
runtime.Portobject connecting the current script to the other extension it is connecting to.
Examples
In this example the extension Hansel connects to the extension Gretel:
console.log("connecting to Gretel"); let myPort = browser.runtime.connect("gretel@mozilla.org"); myPort.onMessage.addListener((message) => { console.log(`From Gretel: ${message.content}`); }); browser.browserAction.onClicked.addListener(() => { myPort.postMessage({ content: "Hello from Hansel" }); }); Gretel listens for the connection and checks that the sender is really Hansel:
let portFromHansel; browser.runtime.onConnectExternal.addListener((port) => { console.log(port); if (port.sender.id === "hansel@mozilla.org") { console.log("connection attempt from Hansel"); portFromHansel = port; portFromHansel.onMessage.addListener((message) => { console.log(`From Hansel: ${message.content}`); }); } }); browser.browserAction.onClicked.addListener(() => { portFromHansel.postMessage({ content: "Message from Gretel" }); }); Browser compatibility
Note: This API is based on Chromium's chrome.runtime API. This documentation is derived from runtime.json in the Chromium code.