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
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Note:
This API is based on Chromium's chrome.runtime API. This documentation is derived from runtime.json in the Chromium code.