How to get the active tab in last focused non-extension window? - google-chrome-extension

Question

I am developing an extension which uses a service worker. The service worker opens a popup window using the usual chrome.windows.create().
During development I have 2 chrome windows open, lets call them A & B. A has tabs of various sites. B has tabs for testing my extension.
Now with a tab in focus in B, I click my extension icon on the toolbar which causes my extension to launch its own window, say C, as discussed above. So there are now in total 3 windows open.
In my extension I want to find the tab id of the active tab in B as that's what was I was focused on when I clicked the extension icon. The following however gives me the tab id of the single tab in C which is my extension's popup
async function getTabId() {
let queryOptions = { active: true, lastFocusedWindow: true };
// `tab` will either be a `tabs.Tab` instance or `undefined`.
let [tab] = await chrome.tabs.query(queryOptions);
console.log(tab)
console.log(tab.title);
return tab.id;
}
Which is fine as I passed lastFocusedWindow: true.
So I pass lastFocusedWindow: false , but that gives me the last focused tab in A!
How do I get the last focused tab in B which was the actual non-extension window in focus before my chrome extension launched its popup?

Answer 1

You can get the active tab before opening the new tab and pass the id via URL:
// background script
(async () => {
const [activeTab] = await chrome.tabs.query({active: true, currentWindow: true});
const params = new URLSearchParams({tabId: activeTab?.id});
const newTab = await chrome.tabs.create({url: 'mypage.html?' + params});
})();
// mypage.js
const tabId = +new URLSearchParams(location.search).get('tabId');