06 Mar 2023
- Iterator: traverses a collection of objects
- Observer:
- A subscription mechanism that notifies multiple objects (one-to-many) about events,
- e.g. subscribe → next in JS.
- Mediator:
- Solves a many-to-many problem,
- Restricts direct communications between the objects and forces them to collaborate only via a mediator object,
- eg. in express middleware that intercepts request.
- State:
- Alternative to a “switch” or “if” statement,
- Finite number of states,
- Closely related to the concept of finite state machines.