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(callback)
-
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. Returns true if it is listening, false otherwise.
Parameters
-
function
-
A callback function that will be called when this event occurs. The function will be passed the following arguments:
-
port
-
A runtime.Port object connecting the current script to the other extension it is connecting to.
Browser compatibility
|
Desktop |
Mobile |
|
Chrome |
Edge |
Firefox |
Internet Explorer |
Opera |
Safari |
WebView Android |
Chrome Android |
Firefox for Android |
Opera Android |
Safari on IOS |
Samsung Internet |
onConnectExternal |
26 |
79 |
54 |
? |
15 |
No |
? |
? |
54 |
? |
No |
? |
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"});
});