HarmonyOS ArkTS Rules

Component Structure

• Use @Component for component definitions and PascalCase for component structs.
• Keep state declarations near the top of the component.
• Group lifecycle hooks before build().
• Place build() last and keep it focused on UI composition.
• Extract complex UI into smaller components.

State and Data Flow

• Use @State for component-owned state.
• Use @Prop for parent-to-child data.
• Use @Link only for intentional two-way binding.
• Keep derived values in methods or computed helpers rather than duplicating state.
• Avoid broad global state unless the project has an established app-state pattern.

Layout and Styling

• Use Column, Row, Stack, List, and other ArkUI primitives intentionally.
• Keep layout properties such as width, height, alignment, and layout weight grouped before visual properties.
• Use object notation for margin and padding when sides differ.
• Use logical pixels consistently.
• Use percentage strings for relative sizes.
• Keep reusable spacing, colors, and typography in resources when the project supports it.

Events and Lifecycle

• Use arrow functions for event handlers.
• Keep event handlers short and delegate complex logic to methods.
• Handle async failures explicitly and surface user-facing errors where appropriate.
• Use lifecycle hooks for setup and teardown that genuinely depends on component lifecycle.

Resources and Accessibility

• Use $r() for app resources.
• Group resource references consistently.
• Add descriptive labels and focus handling for interactive elements.
• Maintain color contrast and touch target size.
• Test on representative device sizes and orientations.

Common Mistakes

• Do not bury business logic in build().
• Do not use two-way binding when one-way props are enough.
• Do not hardcode repeated strings, colors, and dimensions that belong in resources.
• Do not leave debug console.log calls in production code.