How do I let my chrome extension users know when the extension is updated?

Question

I want to show them a popup with the new features.

Answer 1

I have submitted an answer and a working code example here chrome extension first run: Detect Chrome extension first run / update

You get the version from the manifest.json, you store that into your localStorage. In your background page, you check if your version has been set (via undefined) if it isn't set you know that your extension just installed, otherwise if the versions changed, you know it is being updating