I often search for PDF files (Books) in Google using filetype:pdf search operator. Quite often there are multiple spammy PDF files with their link titles being similar to books I am searching for. Those files are ususally much smaller in size compared to book files. So in the book search, the file size could be a reasonably good indicator if this particular PDF link worth a download, or not. I wonder if there is a Chrome browser extension that

How to detect if my Chrome Extension is already installed in user's browser? Using JavaScript? I am a developer of this extension. Thanks!

How to programmatically trigger an installation of Chrome browser extension from the link embedded into email message that our website sends to our users? We want to have as few steps as possible to provide a streamlined user experience. Our extension is hosted in a Chrome Web Store. Please help!