runtime.onConnectExternal
Fired when an extension receives a connection request from a different extension.
To send a message which will be received by theonConnectExternal listener, useruntime.connect(), passing the ID of the recipient in theextensionId parameter.
The listener is passed aruntime.Port object which it can then use to send and receive messages. ThePort object also contains asender property, which is aruntime.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
functionThe function called when this event occurs. The function is passed this argument:
portA
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'schrome.runtime API. This documentation is derived fromruntime.json in the Chromium code.