After preparing the migration of my chrome manifest V2 extension to manifest V3 and reading about the problems with persistent service workers I prepared myself for a battle with the unknown. My V2 background script uses a whole bunch of globally declared variables and I expected I need to refactor that.
But to my great surprise my extension background script seems to work out of the box without any trouble in manifest V3. My extension uses externally_connectable. The typical use case for my extension is that the user can navigate to my website 'bla.com' and from there it can send jobs to the extension background script.
My manifest says:
"externally_connectable": {
"matches": [
"*://localhost/*",
"https://*.bla.com/*"
]
}
My background script listens to external messages and connects:
chrome.runtime.onMessageExternal.addListener( (message, sender, sendResponse) => {
log('received external message', message);
});
chrome.runtime.onConnectExternal.addListener(function(port) {
messageExternalPort = port;
if (messageExternalPort && typeof messageExternalPort.onDisconnect === 'function') {
messageExternalPort.onDisconnect(function () {
messageExternalPort = null;
})
}
});
From bla.com I send messages to the extension as follows
chrome.runtime.sendMessage(EXTENSION_ID, { type: "collect" });
From bla.com I receive messages from the extension as follows
const setUpExtensionListener = () => {
// Connect to chrome extension
this.port = chrome.runtime.connect(EXTENSION_ID, { name: 'query' });
// Add listener
this.port.onMessage.addListener(handleExtensionMessage);
}
I tested all scenarios including the anticipation of the famous service worker unload after 5 minutes or 30 seconds inactivity, but it all seems to work. Good for me, but something is itchy. I cannot find any documentation that explains precisely under which circumstances the service worker is unloaded. I do not understand why things seem to work out of the box in my situation and why so many others experience problems. Can anybody explain or refer to proper documentation. Thanks in advance.
