Redux Essentials => Performance and Normalizing data => adding a badge for notifications

[Reprovo]

When adding a badge for notifications, for the purpose of the course only, we could use !n.new since all notifications are marked as 'read', otherwise the badge doesn't appear. Nothing important but i spent a few minutes trying to see If I had typed something wrong.

const numUnreadNotifications = notifications.filter(n => !n.read).length

[timdorr]

This has already been suggested, but is correct as-is: #4418 (comment)