Delegated Event Handler (E)

Challenge summary

Handle matching descendant events through one listener attached to a stable container.

What you'll practice

• Use event bubbling to avoid one listener per descendant.
• Find the nearest matching target without crossing the container boundary.
• Return an idempotent cleanup operation for the delegated listener.

What Premium unlocks

Premium unlocks the runnable workspace, behavioral checks, implementation walkthrough, and edge-case discussion.