Question

For content scripts in chrome extensions, you can specify matches and exclude_matches to control what pages they are injected in. This has to be specified in the manifest of the extension like this

{
  "name": "Color picker",
  ...
  "content_scripts": [
    {
      "matches": ["http://*/*", "https://*/*"],
      "exclude_matches": ["http://www.google.com/*"],
      "css": ["color_picker.css"],
      "js": ["jquery.js", "color_picker.js"]
    }
  ],
  ...
}

I was wondering if I could add ["http://www.yahoo.com/*"],to exclude_matches as and when the extension is in use. This way, I can allow the user to control the exclude_matches

Answer 1

An extension cannot modify any local files, including the extension’s manifest.json. Chrome offers an API for optional permissions, but this does not include Content scripts.

You can manually create flexible patterns:

// In the content script:
var exclude = /^https?:\/\/(www\.)?yahoo\.com\//;
if (!exclude.test(location.href)) {
     // Run logic.
}

Regular expressions are very powerful for this purpose, though not necessary. Instead of location.href, other location properties, such as location.host can be used.

See also: MDN: window.location.