Here’s an example of a Computed Property from a PR I recently submitted to Ebsy’s excellent National Flags plugin: discourse-nationalflags/assets/javascripts/discourse/components/user-nationalflags-preferences.js.es6 at master · Ebsy/discourse-nationalflags · GitHub
Here’s one (“showTimezones”) that is actually used to hide/show in a template: https://github.com/paviliondev/discourse-team-timezones/blob/master/assets/javascripts/discourse/components/team-display.js.es6
but you’ll find tonnes of great patterns in our plugins: Pavilion · GitHub