vue-best-practices

Vue 3 best practices, common gotchas, and performance optimization.

Reactivity

• Accessing ref() values without .value in scripts → See ref-value-access
• Destructuring reactive() objects, losing reactivity → See reactive-destructuring
• Choosing between ref() and reactive() for state → See prefer-ref-over-reactive
• Accessing refs inside arrays and collections → See refs-in-collections-need-value
• Large objects or external library data overhead → See shallow-ref-for-performance
• Using nested refs in template expressions → See template-ref-unwrapping-top-level
• Comparing reactive objects with === operator → See reactivity-proxy-identity-hazard
• Library instances breaking in reactive state → See reactivity-markraw-for-non-reactive
• Expecting watchers to fire for each state change → See reactivity-same-tick-batching
• Integrating external state management libraries → See reactivity-external-state-integration
• Tracing unexpected re-renders and state updates → See reactivity-debugging-hooks
• Deriving state with watchEffect instead of computed → See reactivity-computed-over-watcheffect-mutations

Computed

• Computed getter is making API calls or mutations → See computed-no-side-effects
• Mutating computed values causes lost changes unexpectedly → See computed-return-value-readonly
• Computed property doesn't update when expected → See computed-conditional-dependencies
• Sorting or reversing arrays destroys original data → See computed-array-mutation
• Expensive operations running too frequently every render → See computed-vs-methods-caching
• Trying to pass arguments to computed properties → See computed-no-parameters
• Complex conditions bloating inline class bindings → See computed-properties-for-class-logic

Watchers

• Need to watch a reactive object property → See watch-reactive-property-getter
• Large nested data structures causing performance issues → See watch-deep-performance
• Async operations overwriting with stale data → See watch-async-cleanup
• Creating watchers inside async callbacks → See watch-async-creation-memory-leak
• Dependencies accessed after await not tracking → See watcheffect-async-dependency-tracking
• Need to access updated DOM in watchers → See watch-flush-timing
• Uncertain whether to use watch or watchEffect → See watch-vs-watcheffect
• Duplicating initial calls and watch callbacks → See watch-immediate-option
• Can't compare old and new values correctly → See watch-deep-same-object-reference
• Template refs appearing null or stale → See watcheffect-flush-post-for-refs

Components

• Prop values being changed from a child component → See props-are-read-only
• Parent can't access child ref data in script setup → See component-ref-requires-defineexpose
• Child component throws "component not found" error → See local-components-not-in-descendants
• Click listener doesn't fire on custom component → See click-events-on-components
• HTML template parsing breaks Vue component syntax → See in-dom-template-parsing-caveats
• Grandparent can't listen to grandchild emitted events → See component-events-dont-bubble
• Wrong component renders due to naming collisions → See component-naming-conflicts
• Distinguishing Vue components from native elements → See component-naming-pascalcase
• Parent styles don't apply to multi-root component → See multi-root-component-class-attrs
• Recursive component needs to reference itself → See self-referencing-component-name
• Bundle includes components that aren't used → See prefer-local-component-registration
• Tight coupling through component ref access → See prefer-props-emit-over-component-refs

Props & Emits

• Boolean prop not parsing as expected → See prop-boolean-casting-order
• Composable doesn't update when props change → See prop-composable-reactivity-loss
• Variables referenced in defineProps cause errors → See prop-defineprops-scope-limitation
• Destructured props not updating watchers → See prop-destructured-watch-getter
• Prop validation needs component instance data → See prop-validation-before-instance
• Component emits undeclared event causing warnings → See declare-emits-for-documentation
• defineEmits used inside function or conditional → See defineEmits-must-be-top-level
• defineEmits has both type and runtime arguments → See defineEmits-no-runtime-and-type-mixed
• Event name inconsistency in templates and scripts → See emit-kebab-case-in-templates
• Event payloads need validation during development → See emit-validation-for-complex-payloads
• Native event listeners not responding to clicks → See native-event-collision-with-emits
• Component event fires twice when clicking → See undeclared-emits-double-firing

Templates

• Rendering untrusted user content as HTML → See v-html-xss-security
• Filtering or conditionally hiding list items → See no-v-if-with-v-for
• List items disappearing or swapping state unexpectedly → See v-for-key-attribute
• Getting template compilation errors with statements → See template-expressions-restrictions
• Dynamic directive arguments not working properly → See dynamic-argument-constraints
• Functions in templates modifying data unexpectedly → See template-functions-no-side-effects
• v-else elements rendering unconditionally always → See v-else-must-follow-v-if
• Child components in loops showing undefined data → See v-for-component-props
• Array order changing after sorting or reversing → See v-for-computed-reverse-sort
• Getting off-by-one errors with range iteration → See v-for-range-starts-at-one
• Performance issues with filtered or sorted lists → See v-for-use-computed-for-filtering
• "Cannot read property of undefined" runtime errors → See v-if-null-check-order
• Deciding between v-if and v-show for conditionals → See v-if-vs-v-show-performance
• v-show or v-else not working on template elements → See v-show-template-limitation

Template Refs

• Ref becomes null when element is conditionally hidden → See template-ref-null-with-v-if
• Ref array indices don't match data array in loops → See template-ref-v-for-order
• Refactoring template ref names breaks silently in code → See use-template-ref-vue35

Forms & v-model

• Initial form values not showing when using v-model → See v-model-ignores-html-attributes
• Textarea content changes not updating the ref → See textarea-no-interpolation
• iOS users cannot select dropdown first option → See select-initial-value-ios-bug
• Parent and child components have different values → See define-model-default-value-sync
• Need to handle v-model modifiers in child → See definemodel-hidden-modifier-props
• Object property changes not syncing to parent → See definemodel-object-mutation-no-emit
• Need to use updated value immediately after change → See definemodel-value-next-tick
• Real-time search/validation broken for Chinese/Japanese input → See v-model-ime-composition
• Number input returns empty string instead of zero → See v-model-number-modifier-behavior
• Migrating Vue 2 components to Vue 3 → See v-model-vue3-breaking-changes
• Custom checkbox values not submitted in forms → See checkbox-true-false-value-form-submission

Events & Modifiers

• Chaining multiple event modifiers produces unexpected results → See event-modifier-order-matters
• Need to handle same event only one time → See event-once-modifier-for-single-use
• Keyboard shortcuts fire with unintended modifier combinations → See exact-modifier-for-precise-shortcuts
• Keyboard shortcuts don't fire with system modifier keys → See keyup-modifier-timing
• Using left-handed mouse or non-standard input devices → See mouse-button-modifiers-intent
• Preventing default browser action and scroll performance together → See no-passive-with-prevent

Lifecycle

• Lifecycle hooks don't execute asynchronously → See lifecycle-hooks-synchronous-registration
• DOM access fails before component mounts → See lifecycle-dom-access-timing
• Memory leaks from unremoved event listeners → See cleanup-side-effects
• SSR rendering differs from client hydration → See lifecycle-ssr-awareness
• Expensive operations slow performance drastically → See updated-hook-performance
• DOM reads return stale values after state changes → See dom-update-timing-nexttick

Slots

• Accessing child component data in slot content → See slot-render-scope-parent-only
• Mixing named and scoped slots together → See slot-named-scoped-explicit-default
• Using v-slot on native HTML elements → See slot-v-slot-on-components-or-templates-only
• Empty wrapper elements rendering unnecessarily → See slot-conditional-rendering-with-slots
• Scoped slot props lack TypeScript type safety → See slot-define-slots-for-typescript
• Rendering empty component slots without defaults → See slot-fallback-content-default-values
• Wrapper components breaking child slot functionality → See slot-forwarding-to-child-components
• Confused about which slot content goes where → See slot-implicit-default-content
• Expecting name property in scoped slot props → See slot-name-reserved-prop
• Choosing between renderless components and composables → See slot-renderless-components-vs-composables

Provide/Inject

• Injected values not updating when provider changes → See provide-inject-reactivity-not-automatic
• Calling provide after async operations fails silently → See provide-inject-synchronous-setup
• String keys collide in large applications → See provide-inject-symbol-keys
• Tracing where provided values come from → See provide-inject-debugging-challenges
• Multiple components share same default object → See provide-inject-default-value-factory
• State mutations scattered across components → See provide-inject-mutations-in-provider
• Passing props through many component layers → See avoid-prop-drilling-use-provide-inject

Attrs

• Both internal and fallthrough event handlers execute → See attrs-event-listener-merging
• Accessing hyphenated attributes in JavaScript code → See attrs-hyphenated-property-access
• Watching fallthrough attributes for changes with watch() → See attrs-not-reactive
• Explicit attributes overwritten by fallthrough values → See fallthrough-attrs-overwrite-vue3
• Attributes applying to wrong element in wrappers → See inheritattrs-false-for-wrapper-components

Composables

• Composable has unexpected side effects affecting external state → See composable-avoid-hidden-side-effects
• Composable called outside setup context or asynchronously → See composable-call-location-restrictions
• Building complex logic from smaller focused composables → See composable-composition-pattern
• Inconsistent composable names or destructuring loses reactivity → See composable-naming-return-pattern
• Composable has many optional parameters or confusing argument order → See composable-options-object-pattern
• Need to prevent uncontrolled mutations of composable state → See composable-readonly-state
• Composable reactive dependency not updating when input changes → See composable-tovalue-inside-watcheffect
• Unsure whether logic belongs in composable or utility function → See composable-vs-utility-functions

Composition API

• Optimizing production bundle size and performance → See composition-api-bundle-size-minification
• Composition API code becoming scattered and hard to maintain → See composition-api-code-organization
• Fixing naming conflicts and unclear data origins in mixins → See composition-api-mixins-replacement
• Applying functional patterns incorrectly to Vue state → See composition-api-not-functional-programming
• Gradually migrating large Options API codebase → See composition-api-options-api-coexistence
• Lifecycle hooks failing silently after async operations → See composition-api-script-setup-async-context
• Coming from React, over-engineering Vue patterns unnecessarily → See composition-api-vs-react-hooks-differences
• Parent component refs unable to access exposed properties → See define-expose-before-await

Directives

• Storing state across directive hooks → See directive-arguments-read-only
• Applying custom directives to Vue components → See directive-avoid-on-components
• Creating intervals or event listeners in directives → See directive-cleanup-in-unmounted
• Simplifying directives with identical behavior → See directive-function-shorthand
• Using custom directives in script setup → See directive-naming-v-prefix
• Choosing between custom and built-in directives → See directive-prefer-declarative-templating
• Deciding between directives and components → See directive-vs-component-decision
• Migrating Vue 2 directives to Vue 3 → See directive-vue2-migration-hooks

Transitions

• Wrapping multiple elements or components in transitions → See transition-single-element-slot
• Transitioning between same element types without animation → See transition-key-for-same-element
• Using JavaScript animations without calling done callback → See transition-js-hooks-done-callback
• Animating lists with TransitionGroup without unique keys → See transition-group-key-requirement
• Performance problems with janky list animations → See transition-animate-transform-opacity
• Move animations failing on inline list elements → See transition-group-flip-inline-elements
• List items jumping instead of smoothly animating → See transition-group-move-animation-position-absolute
• Vue 2 to Vue 3 transition layout breaks unexpectedly → See transition-group-no-default-wrapper-vue3
• Trying to sequence list animations with mode prop → See transition-group-no-mode-prop
• Creating cascading delays for list item animations → See transition-group-staggered-animations
• Overlapping elements or layout jumping during transitions → See transition-mode-out-in
• Nested transition animations cutting off prematurely → See transition-nested-duration
• Reusable transition components with scoped styles breaking → See transition-reusable-scoped-style
• RouterView transitions unexpectedly animating on page load → See transition-router-view-appear
• Mixing CSS transitions and animations causing timing issues → See transition-type-when-mixed
• Component cleanup not firing during fast transition replacements → See transition-unmount-hook-timing

Animation

• Need to animate elements staying in DOM → See animation-class-based-technique
• Animations not triggering on content changes → See animation-key-for-rerender
• Building interactive animations with user input → See animation-state-driven-technique
• Animating list changes causing noticeable lag → See animation-transitiongroup-performance

KeepAlive

• Using KeepAlive without proper cache limits or cleanup → See keepalive-memory-management
• KeepAlive include/exclude props not matching cached components → See keepalive-component-name-requirement
• Need to programmatically remove component from KeepAlive cache → See keepalive-no-cache-removal-vue3
• Users see stale cached content when expecting fresh page data → See keepalive-router-fresh-vs-cached
• Child components mount twice with nested Vue Router routes → See keepalive-router-nested-double-mount
• Memory grows when combining KeepAlive with Transition animations → See keepalive-transition-memory-leak
• Dynamic component state resets when switching between them → See dynamic-components-with-keepalive

Async Components

• Setting up Vue Router route component loading → See async-component-vue-router
• Async component options ignored by parent Suspense → See async-component-suspense-control
• Network failures or timeouts loading components → See async-component-error-handling
• Improving Time to Interactive with SSR apps → See async-component-hydration-strategies
• Template refs undefined after component reactivation → See async-component-keepalive-ref-issue
• Loading spinner flashing on fast networks → See async-component-loading-delay