
What is a reaction?
A reaction responds to an occurance of an event by invoking a command.
A reaction responds to an occurance of an event by invoking a command.
Use this pattern every time something needs to happen in reaction to something else that happened before.
Check out the quickstart for a quick example.
Or get started with the learning path, where you'll build both a transient reaction in lesson 8 and a guaranteed reaction in lesson 9.