API intended for external developers or users.

Loading resources only when required.

Special value representing absence of an object or value.

Restricting how frequently operations may occur.

Testing behavior under expected workload levels.

Reusable collection of initialized objects.

Programming style based on asynchronous data streams and events.

Browser storage for persistent client-side data.

Component that receives notifications about another object's changes.

Data or resource that cannot normally be modified.