Computed properties are dynamic properties and are helpful for deriving values from a database or another persistent store like a cache.
Computed properties are similar to Data Properties with some key differences:
They are declared as inline functions using computed.
Computed properties are cached for the lifetime of the request. Meaning, if you reference your computed property three times in your Template or from within a component Action, it will only execute once.
You can define computed properties in your components using computed. Each computed property is invoked only once during a single request cycle.