Vue Best Practices

1.1 Must-read core references (required)

• Before implementing any Vue task, make sure to read and apply these core references:
  • references/reactivity.md
  • references/sfc.md
  • references/component-data-flow.md
  • references/composables.md
• Keep these references in active working context for the entire task, not only when a specific issue appears.

1.2 Plan component boundaries before coding (required)

Create a brief component map before implementation for any non-trivial feature.

• Define each component's single responsibility in one sentence.
• Keep entry/root and route-level view components as composition surfaces by default.
• Move feature UI and feature logic out of entry/root/view components unless the task is intentionally a tiny single-file demo.
• Define props/emits contracts for each child component in the map.
• Prefer a feature folder layout (components/<feature>/..., composables/use<Feature>.ts) when adding more than one component.

2) Apply essential Vue foundations (required)

These are essential, must-know foundations. Apply all of them in every Vue task using the core references already loaded in section 1.1.

Reactivity

• Must-read reference from 1.1: reactivity
• Keep source state minimal (ref/reactive), derive everything possible with computed.
• Use watchers for side effects if needed.
• Avoid recomputing expensive logic in templates.

SFC structure and template safety

• Must-read reference from 1.1: sfc
• Keep SFC sections in this order: <script> → <template> → <style>.
• Keep SFC responsibilities focused; split large components.
• Keep templates declarative; move branching/derivation to script.
• Apply Vue template safety rules (v-html, list rendering, conditional rendering choices).

Keep components focused

Split a component when it has more than one clear responsibility (e.g. data orchestration + UI, or multiple independent UI sections).

• Prefer smaller components + composables over one “mega component”
• Move UI sections into child components (props in, events out).
• Move state/side effects into composables (useXxx()).

Apply objective split triggers. Split the component if any condition is true:

• It owns both orchestration/state and substantial presentational markup for multiple sections.
• It has 3+ distinct UI sections (for example: form, filters, list, footer/status).
• A template block is repeated or could become reusable (item rows, cards, list entries).

Entry/root and route view rule:

• Keep entry/root and route view components thin: app shell/layout, provider wiring, and feature composition.
• Do not place full feature implementations in entry/root/view components when those features contain independent parts.
• For CRUD/list features (todo, table, catalog, inbox), split at least into:
  • feature container component
  • input/form component
  • list (and/or item) component
  • footer/actions or filter/status component
• Allow a single-file implementation only for very small throwaway demos; if chosen, explicitly justify why splitting is unnecessary.

Component data flow

• Must-read reference from 1.1: component-data-flow
• Use props down, events up as the primary model.
• Use v-model only for true two-way component contracts.
• Use provide/inject only for deep-tree dependencies or shared context.
• Keep contracts explicit and typed with defineProps, defineEmits, and InjectionKey as needed.

Composables

• Must-read reference from 1.1: composables
• Extract logic into composables when it is reused, stateful, or side-effect heavy.
• Keep composable APIs small, typed, and predictable.
• Separate feature logic from presentational components.

3) Consider optional features only when requirements call for them

3.1 Standard optional features

Do not add these by default. Load the matching reference only when the requirement exists.

• Slots: parent needs to control child content/layout -> component-slots
• Fallthrough attributes: wrapper/base components must forward attrs/events safely -> component-fallthrough-attrs
• Built-in component <KeepAlive> for stateful view caching -> component-keep-alive
• Built-in component <Teleport> for overlays/portals -> component-teleport
• Built-in component <Suspense> for async subtree fallback boundaries -> component-suspense
• Animation-related features: pick the simplest approach that matches the required motion behavior.
  • Built-in component <Transition> for enter/leave effects -> transition
  • Built-in component <TransitionGroup> for animated list mutations -> transition-group
  • Class-based animation for non-enter/leave effects -> animation-class-based-technique
  • State-driven animation for user-input-driven animation -> animation-state-driven-technique

3.2 Less-common optional features

Use these only when there is explicit product or technical need.

• Directives: behavior is DOM-specific and not a good composable/component fit -> directives
• Async components: heavy/rarely-used UI should be lazy loaded -> component-async
• Render functions only when templates cannot express the requirement -> render-functions
• Plugins when behavior must be installed app-wide -> plugins
• State management patterns: app-wide shared state crosses feature boundaries -> state-management

4) Run performance optimization after behavior is correct

Performance work is a post-functionality pass. Do not optimize before core behavior is implemented and verified.

• Large list rendering bottlenecks -> perf-virtualize-large-lists
• Static subtrees re-rendering unnecessarily -> perf-v-once-v-memo-directives
• Over-abstraction in hot list paths -> perf-avoid-component-abstraction-in-lists
• Expensive updates triggered too often -> updated-hook-performance

5) Final self-check before finishing

• Core behavior works and matches requirements.
• All must-read references were read and applied.
• Reactivity model is minimal and predictable.
• SFC structure and template rules are followed.
• Components are focused and well-factored, splitting when needed.
• Entry/root and route view components remain composition surfaces unless there is an explicit small-demo exception.
• Component split decisions are explicit and defensible (responsibility boundaries are clear).
• Data flow contracts are explicit and typed.
• Composables are used where reuse/complexity justifies them.
• Moved state/side effects into composables if applicable
• Optional features are used only when requirements demand them.
• Performance changes were applied only after functionality was complete.