Browser extensions provide custom features to the browser and web pages.
You can create a browser extension to inject a script to do what you want on a site.
Use web-ext-create to start a new project.
https://www.npmjs.com/package/create-web-ext
Use the web-ext tool to begin development.
https://github.com/mozilla/web-ext
Web-ext will reload changes you make live in the browser.
Customize web-ext-config.js to specify a profile to use.
Create a profile with the extensions you want and save it for future use.
When configuring the profile, use --keep-profile-changes to set it up, and then run without the flag once configured.
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