Stimulus Fundamentals

Implement robust Stimulus controllers with clear lifecycle and state boundaries.

Core Workflow

1. Define controller contract first: targets, values, outlets, actions, and expected lifecycle.
2. Keep state transitions in value callbacks when reactive updates are required.
3. Guard callbacks that can run before connect() completes.
4. Use connect()/disconnect() for setup and teardown symmetry.
5. Isolate DOM event handling from business rules; keep controllers composable.

Guardrails

• Prefer declarative action parameters over manual dataset parsing.
• Use outlets for controller-to-controller communication instead of private internals.
• Keep target callbacks idempotent; account for repeated connect/disconnect cycles.
• Use MutationObserver only when DOM-driven reactivity is required.
• Feature-detect browser APIs before exposing UI affordances.