There’s a way to allow a content script heavy extension to continue functioning after an upgrade, and to make it work immediately upon installation.
Install/upgrade
The install method is to simply iterate through all tabs in all windows, and inject some scripts programmatically into tabs with matching URLs.
Obviously, you have to do it in a background page or event page script declared in manifest.json:
"background": {
"scripts": ["background.js"]
},
background.js:
// Add a `manifest` property to the `chrome` object.
chrome.manifest = chrome.runtime.getManifest();
var injectIntoTab = function (tab) {
// You could iterate through the content scripts here
var scripts = chrome.manifest.content_scripts[0].js;
var i = 0, s = scripts.length;
for( ; i < s; i++ ) {
chrome.tabs.executeScript(tab.id, {
file: scripts[i]
});
}
}
// Get all windows
chrome.windows.getAll({
populate: true
}, function (windows) {
var i = 0, w = windows.length, currentWindow;
for( ; i < w; i++ ) {
currentWindow = windows[i];
var j = 0, t = currentWindow.tabs.length, currentTab;
for( ; j < t; j++ ) {
currentTab = currentWindow.tabs[j];
// Skip chrome:// and https:// pages
if( ! currentTab.url.match(/(chrome|https):\/\//gi) ) {
injectIntoTab(currentTab);
}
}
}
});
ManifestV3
manifest.json:
"background": {"service_worker": "background.js"},
"permissions": ["scripting"],
"host_permissions": ["<all_urls"],
These host_permissions should be the same as the content script’s matches
.
background.js:
chrome.runtime.onInstalled.addListener(async () => {
for (const cs of chrome.runtime.getManifest().content_scripts) {
for (const tab of await chrome.tabs.query({url: cs.matches})) {
chrome.scripting.executeScript({
target: {tabId: tab.id},
files: cs.js,
});
}
}
});
This is a simplified example that doesn’t handle frames. You can use getAllFrames API and match the URLs yourself, see the documentation for matching patterns.
Historical trivia
In ancient Chrome 26 and earlier content scripts could restore connection to the background script. It was fixed http://crbug.com/168263 in 2013. You can see an example of this trick in the earlier revisions of this answer.