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
listener
argument is the listener to remove. hasListener(listener)
-
Checks whether a
listener
is registered for this event. Returnstrue
if it is listening,false
otherwise.
addListener syntax
Parameters
function
-
The function called when this event occurs. The function is passed this argument:
port
-
A
runtime.Port
object connecting the current script to the other extension it is connecting to.
Browser compatibility
BCD tables only load in the browser
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" });
});
Note:
This API is based on Chromium's chrome.runtime
API. This documentation is derived from runtime.json
in the Chromium code.