Svelte Interview Questions Your Guide to Success

Svelte's unique compile-time approach and reactive programming model make it a powerful framework for modern web development. Stark.ai offers a comprehensive collection of Svelte interview questions, real-world scenarios, and expert guidance to help you excel in your next technical interview.

Svelte Basics & Components 10
Reactivity & State Management 8
Props & Component Communication 10
Lifecycle Methods 10
Events & Event Handling 10
Stores & Global State 10
Transitions & Animations 10
Slots & Content Projection 17
Routing in Svelte (SvelteKit) 9
Context API & Dependencies 9
Bindings & Directives 9
Server Side Rendering (SSR) 9
Testing & Debugging 10
Performance & Optimization 9

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typescript

vuejs

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svelte

Svelte Basics & Components
- How do you implement two-way binding in Svelte?
  
  Two-way binding is implemented using the bind: directive. Common with form elements. Example: <input...
- How do you handle component initialization logic?
  
  Component initialization is handled in the <script> section. Can use onMount lifecycle function for side effects....
- What are derived stores in Svelte?
  
  Derived stores are created using derived() function, combining one or more stores into a new one. Values update...
- How do you implement dynamic component loading?
  
  Dynamic components can be loaded using svelte:component directive. Example: <svelte:component...
- What are actions in Svelte?
  
  Actions are reusable functions that run when an element is created. Used with use: directive. Can return destroy...
- How do you handle component composition patterns?
  
  Component composition patterns include slots, context API, event forwarding. Support nested components, higher-order...
- What is the purpose of reactive statements?
  
  Reactive statements ($:) automatically re-run when dependencies change. Used for derived calculations and side...
- How do you implement component interfaces?
  
  Component interfaces use TypeScript with props and events. Define prop types using export let prop: Type. Support...
- What are component lifecycle methods?
  
  Lifecycle methods include onMount, onDestroy, beforeUpdate, afterUpdate. Handle component initialization, cleanup,...
- How do you handle component state persistence?
  
  State persistence uses local storage, session storage, or external stores. Implement auto-save functionality. Handle...
Reactivity & State Management
- How do you implement derived stores?
  
  Derived stores are created using derived() from svelte/store. Take one or more stores as input. Transform values...
- How do you handle async derived stores?
  
  Async derived stores handle asynchronous transformations. Use derived with set callback. Handle loading states....
- How do you implement custom stores?
  
  Custom stores implement subscribe function. Can add custom methods. Handle internal state. Support custom update...
- How do you handle store initialization?
  
  Store initialization can be synchronous or async. Handle initial values. Support lazy initialization. Manage loading...
- How do you implement store persistence?
  
  Store persistence uses localStorage or sessionStorage. Implement auto-save functionality. Handle serialization....
- How do you handle store subscriptions cleanup?
  
  Store subscriptions cleanup happens automatically with $ prefix. Manual cleanup needs unsubscribe call. Handle...
- How do you handle store error states?
  
  Store error handling includes error states. Implement error recovery. Support error notifications. Handle async...
- How do you implement store middleware?
  
  Store middleware intercepts store operations. Implement custom behaviors. Handle side effects. Support middleware...
Props & Component Communication
- How do you implement prop type checking?
  
  Prop types can be checked using TypeScript or runtime validation. Define interfaces for props. Implement validation...
- How do you handle async props?
  
  Async props can be handled using promises or async/await. Handle loading states. Use reactive statements for async...
- What are computed props?
  
  Computed props derive values from other props using reactive declarations. Example: $: fullName = `${firstName}...
- How do you implement prop watchers?
  
  Prop watchers use reactive statements to observe changes. Can trigger side effects or validations. Handle prop...
- How do you handle prop defaults?
  
  Prop defaults are set in export statement or computed. Consider component initialization. Handle undefined values....
- What are event modifiers?
  
  Event modifiers customize event behavior. Include preventDefault, stopPropagation, once, capture. Used with on:...
- How do you implement prop transformation?
  
  Prop transformation converts prop values before use. Use computed properties or methods. Handle data formatting....
- What are dynamic event handlers?
  
  Dynamic event handlers change based on props or state. Use computed values for handlers. Support conditional events....
- How do you implement prop persistence?
  
  Prop persistence saves prop values between renders. Use stores or local storage. Handle persistence lifecycle....
- What are compound components?
  
  Compound components share state through context. Implement parent-child communication. Handle component composition....
Lifecycle Methods
- How do you handle errors in lifecycle methods?
  
  Error handling uses try/catch blocks or error boundaries. Handle async errors appropriately. Implement error...
- How do you manage state initialization in lifecycle methods?
  
  State initialization happens in component creation or onMount. Handle async initialization. Support loading states....
- How do lifecycle methods interact with stores?
  
  Store subscriptions are typically set up in onMount and cleaned in onDestroy. Handle store updates. Support...
- How do you handle DOM measurements in lifecycle methods?
  
  DOM measurements use afterUpdate for accurate values. Cache measurements when needed. Handle resize events. Support...
- How do you implement initialization patterns?
  
  Initialization patterns include lazy loading, conditional initialization, and dependency injection. Handle...
- How do you handle prop changes in lifecycle methods?
  
  Prop changes trigger beforeUpdate and afterUpdate. Implement prop watchers. Handle derived values. Support prop...
- How do you manage side effects in lifecycle methods?
  
  Side effects management includes cleanup, ordering, and dependencies. Handle async side effects. Support...
- How do lifecycle methods work with animations?
  
  Animations interact with beforeUpdate and afterUpdate. Handle transition states. Support animation cleanup....
- How do you implement lifecycle hooks?
  
  Lifecycle hooks extend default lifecycle behavior. Implement custom hooks. Support hook composition. Handle hook...
- How do you handle component transitions?
  
  Component transitions use lifecycle methods for coordination. Handle mount/unmount animations. Support transition...
Events & Event Handling
- How do you implement event debouncing?
  
  Event debouncing delays handler execution. Use timer to postpone execution. Clear previous timer on new events....
- How do you implement event throttling?
  
  Event throttling limits execution frequency. Implement using timer and last execution time. Ensure minimum time...
- How do you handle keyboard events?
  
  Keyboard events use on:keydown, on:keyup, on:keypress. Access key information through event.key. Support key...
- How do you handle drag and drop events?
  
  Drag and drop uses dragstart, dragover, drop events. Set draggable attribute. Handle data transfer. Support drag...
- How do you handle form events?
  
  Form events include submit, reset, change. Prevent default submission. Handle validation. Collect form data. Support...
- How do you implement custom event modifiers?
  
  Custom modifiers use actions (use:). Implement modifier logic. Support parameters. Handle cleanup. Share across components.
- How do you handle outside clicks?
  
  Outside clicks check event.target relationship. Implement using actions. Handle document clicks. Support multiple...
- How do you handle touch events?
  
  Touch events include touchstart, touchmove, touchend. Handle gestures. Support multi-touch. Implement touch...
- How do you handle scroll events?
  
  Scroll events track scroll position. Implement scroll handlers. Support infinite scroll. Handle scroll optimization....
- How do you handle window events?
  
  Window events use svelte:window component. Listen to resize, scroll, online/offline. Handle cleanup. Support event...
Stores & Global State
- How do you implement custom stores?
  
  Custom stores implement subscribe method. Can add custom methods. Handle internal state. Example: function...
- How do you handle async stores?
  
  Async stores handle asynchronous data. Support loading states. Handle errors. Example: const data = writable(null);...
- How do you implement store persistence?
  
  Store persistence saves state to storage. Implement auto-save. Handle state rehydration. Example: Subscribe to...
- How do you handle store dependencies?
  
  Store dependencies use derived stores or reactive statements. Handle update order. Manage circular dependencies....
- How do you implement store middleware?
  
  Store middleware intercepts store operations. Implement custom behaviors. Handle side effects. Example: Create...
- How do you handle store errors?
  
  Store error handling catches and processes errors. Implement error states. Support error recovery. Example:...
- How do you implement store validation?
  
  Store validation ensures valid state. Implement validation rules. Handle validation errors. Example: Create wrapper...
- How do you optimize store updates?
  
  Store optimization includes batching updates, debouncing, throttling. Handle performance bottlenecks. Example:...
- How do you implement store composition?
  
  Store composition combines multiple stores. Create higher-order stores. Handle store relationships. Example: Combine...
- How do you manage store lifecycles?
  
  Store lifecycle management handles initialization, updates, cleanup. Support store creation/destruction. Example:...
Transitions & Animations
- How do you create custom transitions?
  
  Custom transitions are functions returning animation parameters. Include css and tick functions. Handle enter/exit...
- How do you handle transition events?
  
  Transition events include introstart, introend, outrostart, outroend. Listen using on: directive. Example: <div...
- What are CSS animations in Svelte?
  
  CSS animations use standard CSS animation properties. Can be combined with transitions. Example: <div animate:flip>....
- How do you use the flip animation?
  
  Flip animation smoothly animates layout changes. Example: <div animate:flip>. Parameters include duration, delay....
- How do you handle multiple transitions?
  
  Multiple transitions can be combined using different directives. Handle timing coordination. Support transition...
- How do you implement spring animations?
  
  Spring animations use spring() function. Handle physics-based animations. Support stiffness and damping. Example:...
- How do you handle transition crossfade?
  
  Crossfade creates smooth transitions between elements. Use crossfade() function. Handle element replacement. Support...
- How do you optimize transition performance?
  
  Optimize using CSS transforms, will-change property. Handle hardware acceleration. Manage animation frame rate....
- How do you handle transition groups?
  
  Transition groups coordinate multiple transitions. Handle group timing. Support synchronized animations. Manage...
- How do you implement deferred transitions?
  
  Deferred transitions delay animation start. Handle transition timing. Support conditional transitions. Manage...
Slots & Content Projection
- How do you implement conditional slots?
  
  Conditional slots use if blocks around slots. Handle slot presence checks. Support dynamic slot selection. Example:...
- How do you handle dynamic slot names?
  
  Dynamic slot names use computed values. Support runtime slot selection. Handle dynamic content projection. Example:...
- How do you implement slot validation?
  
  Slot validation checks content type and structure. Handle invalid content. Support content restrictions. Implement...
- How do you handle slot events?
  
  Slot events bubble through component hierarchy. Handle event forwarding. Support event modification. Manage event...
- How do you handle slot lifecycles?
  
  Slot lifecycles manage content updates. Handle content mounting/unmounting. Support cleanup operations. Manage slot state.
- How do you implement slot composition?
  
  Slot composition combines multiple slots. Handle nested slots. Support slot inheritance. Implement composition patterns.
- How do you optimize slot performance?
  
  Slot optimization improves rendering efficiency. Handle content caching. Support lazy loading. Manage update frequency.
- How do you handle slot error boundaries?
  
  Error boundaries catch slot content errors. Handle error recovery. Support fallback content. Manage error state.
- How do you implement conditional slots?
  
  Conditional slots use if blocks around slots. Handle slot presence checks. Support dynamic slot selection. Example:...
- How do you handle dynamic slot names?
  
  Dynamic slot names use computed values. Support runtime slot selection. Handle dynamic content projection. Example:...
- How do you implement slot validation?
  
  Slot validation checks content type and structure. Handle invalid content. Support content restrictions. Implement...
- How do you handle slot events?
  
  Slot events bubble through component hierarchy. Handle event forwarding. Support event modification. Manage event...
- How do you implement slot middleware?
  
  Slot middleware processes slot content. Handle content transformation. Support content filtering. Implement middleware chain.
- How do you handle slot lifecycles?
  
  Slot lifecycles manage content updates. Handle content mounting/unmounting. Support cleanup operations. Manage slot state.
- How do you implement slot composition?
  
  Slot composition combines multiple slots. Handle nested slots. Support slot inheritance. Implement composition patterns.
- How do you optimize slot performance?
  
  Slot optimization improves rendering efficiency. Handle content caching. Support lazy loading. Manage update frequency.
- How do you handle slot error boundaries?
  
  Error boundaries catch slot content errors. Handle error recovery. Support fallback content. Manage error state.
Routing in Svelte (SvelteKit)
- How do you implement route guards?
  
  Route guards protect routes using load functions. Check authentication/authorization. Return redirect for...
- How do you handle nested layouts?
  
  Nested layouts use multiple +layout.svelte files. Each level adds layout. Support layout inheritance. Handle layout...
- How do you implement route preloading?
  
  Preloading uses data-sveltekit-preload attribute. Fetches data before navigation. Support hover preloading. Handle...
- How do you handle route transitions?
  
  Route transitions use page transitions API. Support enter/leave animations. Handle transition lifecycle. Implement...
- How do you implement route middleware?
  
  Route middleware uses hooks.server.js file. Handle request/response. Support authentication. Implement custom logic....
- How do you handle route caching?
  
  Route caching implements caching strategies. Handle data caching. Support page caching. Implement cache...
- How do you implement route validation?
  
  Route validation handles parameter validation. Support request validation. Implement validation rules. Handle...
- How do you handle route state?
  
  Route state management uses stores or context. Handle state persistence. Support state sharing. Implement state...
- How do you optimize route performance?
  
  Route optimization includes code splitting, preloading. Handle lazy loading. Support route prioritization. Implement...
Context API & Dependencies
- How do you implement context patterns?
  
  Context patterns include provider components, dependency injection, service locator. Handle context composition....
- How do you handle context updates?
  
  Context updates require component reinitialization. Can combine with stores for reactive updates. Handle update...
- How do you handle context dependencies?
  
  Context dependencies manage relationships between contexts. Handle dependency order. Support circular dependencies....
- How do you implement context composition?
  
  Context composition combines multiple contexts. Handle context merging. Support context inheritance. Implement...
- How do you handle context initialization?
  
  Context initialization sets up initial context state. Handle async initialization. Support initialization order....
- How do you implement context middleware?
  
  Context middleware processes context operations. Handle context transformation. Support middleware chain. Implement...
- How do you handle context errors?
  
  Context error handling manages error states. Handle missing context. Support error recovery. Implement error boundaries.
- How do you optimize context usage?
  
  Context optimization improves performance. Handle context caching. Support selective updates. Implement optimization...
- How do you handle context cleanup?
  
  Context cleanup manages resource disposal. Handle cleanup order. Support cleanup hooks. Implement cleanup strategies.
Bindings & Directives
- How do you implement custom actions?
  
  Custom actions are functions returning optional destroy method. Handle DOM node manipulation. Support parameters....
- How do you handle binding validation?
  
  Binding validation ensures valid values. Handle input constraints. Support custom validation. Implement error...
- How do you implement binding middleware?
  
  Binding middleware processes binding operations. Handle value transformation. Support validation chain. Implement...
- How do you handle binding dependencies?
  
  Binding dependencies manage related bindings. Handle dependency updates. Support dependency tracking. Implement...
- How do you optimize binding performance?
  
  Binding optimization improves update efficiency. Handle update batching. Support selective updates. Implement...
- How do you implement custom directives?
  
  Custom directives extend element functionality. Handle directive lifecycle. Support directive parameters. Implement...
- How do you handle binding errors?
  
  Binding error handling manages invalid states. Handle error recovery. Support error notifications. Implement error...
- How do you implement binding composition?
  
  Binding composition combines multiple bindings. Handle binding interaction. Support binding inheritance. Implement...
- How do you handle binding cleanup?
  
  Binding cleanup manages resource disposal. Handle cleanup order. Support cleanup hooks. Implement cleanup strategies.
Server Side Rendering (SSR)
- How do you implement SSR data fetching?
  
  SSR data fetching uses load functions. Handle async operations. Support caching strategies. Implement error...
- How do you handle SSR caching?
  
  SSR caching implements cache strategies. Handle cache invalidation. Support cache headers. Implement cache storage....
- How do you optimize SSR performance?
  
  SSR optimization includes code splitting, caching, streaming. Handle resource optimization. Support performance...
- How do you handle SSR session state?
  
  SSR session state manages user sessions. Handle session storage. Support session persistence. Implement session...
- How do you implement SSR middleware?
  
  SSR middleware processes server requests. Handle request transformation. Support middleware chain. Implement...
- How do you handle SSR authentication?
  
  SSR authentication manages user auth state. Handle auth flows. Support session management. Implement auth...
- How do you implement SSR routing?
  
  SSR routing handles server-side navigation. Handle route matching. Support dynamic routes. Implement routing...
- How do you handle SSR headers?
  
  SSR headers manage HTTP headers. Handle cache control. Support content types. Implement header strategies. Manage...
- How do you implement SSR forms?
  
  SSR forms handle form submissions server-side. Handle form validation. Support file uploads. Implement CSRF...
Testing & Debugging
- How do you implement integration testing?
  
  Integration testing verifies component interaction. Test multiple components. Handle data flow. Implement test...
- How do you test stores?
  
  Store testing verifies store behavior. Test store updates. Handle subscriptions. Implement store mock. Manage store state.
- How do you implement test mocks?
  
  Test mocks simulate dependencies. Handle external services. Support mock responses. Implement mock behavior. Manage...
- How do you test routing?
  
  Route testing verifies navigation behavior. Test route parameters. Handle route changes. Implement navigation tests....
- How do you handle test fixtures?
  
  Test fixtures provide test data. Handle data setup. Support test isolation. Implement fixture management. Manage...
- How do you test animations?
  
  Animation testing verifies transition behavior. Test animation states. Handle animation timing. Implement animation...
- How do you implement test hooks?
  
  Test hooks handle test lifecycle. Support setup/teardown. Implement test utilities. Manage test state. Handle test...
- How do you test error handling?
  
  Error handling testing verifies error states. Test error boundaries. Handle error recovery. Implement error...
- How do you handle test coverage?
  
  Test coverage tracks code coverage. Generate coverage reports. Set coverage targets. Implement coverage checks....
- How do you implement test organization?
  
  Test organization structures test files. Group related tests. Support test discovery. Implement naming conventions....
Performance & Optimization
- How do you implement caching strategies?
  
  Caching strategies include browser cache, service workers, SSR cache. Handle cache invalidation. Support offline...
- How do you optimize animations?
  
  Animation optimization includes using CSS animations when possible, hardware acceleration, efficient transitions....
- How do you handle large lists?
  
  Large list optimization includes virtual scrolling, pagination, infinite scroll. Use keyed each blocks. Implement...
- How do you optimize image loading?
  
  Image optimization includes lazy loading, responsive images, proper formats. Use srcset attribute. Implement...
- How do you implement performance monitoring?
  
  Performance monitoring tracks metrics like load time, FCP, TTI. Use browser DevTools. Implement analytics. Handle...
- How do you optimize SSR performance?
  
  SSR optimization includes caching, streaming, efficient data loading. Handle server resources. Implement response...
- How do you handle resource prioritization?
  
  Resource prioritization includes critical CSS, script loading strategies, preload/prefetch. Handle resource order....
- How do you optimize build configuration?
  
  Build optimization includes proper Vite/Rollup config, production settings, environment optimization. Handle build...
- How do you handle performance testing?
  
  Performance testing measures load time, interaction time, resource usage. Implement benchmarks. Handle performance...

How do you implement two-way binding in Svelte?

Two-way binding is implemented using the bind: directive. Common with form elements. Example: <input bind:value={name}>. Supports binding to different properties like checked for checkboxes.

How do you handle component initialization logic?

Component initialization is handled in the <script> section. Can use onMount lifecycle function for side effects. Top-level code runs on component creation. Support async initialization using IIFE or onMount.

What are derived stores in Svelte?

Derived stores are created using derived() function, combining one or more stores into a new one. Values update automatically when source stores change. Support synchronous and asynchronous derivation.

How do you implement dynamic component loading?

Dynamic components can be loaded using svelte:component directive. Example: <svelte:component this={dynamicComponent} />. Support lazy loading using import(). Handle loading states.

What are actions in Svelte?

Actions are reusable functions that run when an element is created. Used with use: directive. Can return destroy function. Example: <div use:tooltip={params}>. Support custom DOM manipulation.

How do you handle component composition patterns?

Component composition patterns include slots, context API, event forwarding. Support nested components, higher-order components. Handle component communication through props and events.

What is the purpose of reactive statements?

Reactive statements ($:) automatically re-run when dependencies change. Used for derived calculations and side effects. Support multiple dependencies. Handle complex reactive computations.

How do you implement component interfaces?

Component interfaces use TypeScript with props and events. Define prop types using export let prop: Type. Support interface inheritance. Handle optional props and default values.

What are component lifecycle methods?

Lifecycle methods include onMount, onDestroy, beforeUpdate, afterUpdate. Handle component initialization, cleanup, updates. Support async operations. Manage side effects.

How do you handle component state persistence?

State persistence uses local storage, session storage, or external stores. Implement auto-save functionality. Handle state rehydration. Support offline state management.

How do you implement derived stores?

Derived stores are created using derived() from svelte/store. Take one or more stores as input. Transform values using callback function. Update automatically when source stores change.

How do you handle async derived stores?

Async derived stores handle asynchronous transformations. Use derived with set callback. Handle loading states. Support cancellation. Manage async dependencies.

How do you implement custom stores?

Custom stores implement subscribe function. Can add custom methods. Handle internal state. Support custom update logic. Implement cleanup on unsubscribe.

How do you handle store initialization?

Store initialization can be synchronous or async. Handle initial values. Support lazy initialization. Manage loading states. Handle initialization errors.

How do you implement store persistence?

Store persistence uses localStorage or sessionStorage. Implement auto-save functionality. Handle serialization. Support state rehydration. Manage persistence errors.

How do you handle store subscriptions cleanup?

Store subscriptions cleanup happens automatically with $ prefix. Manual cleanup needs unsubscribe call. Handle cleanup in onDestroy. Prevent memory leaks.

How do you handle store error states?

Store error handling includes error states. Implement error recovery. Support error notifications. Handle async errors. Manage error boundaries.

How do you implement store middleware?

Store middleware intercepts store operations. Implement custom behaviors. Handle side effects. Support middleware chain. Manage middleware order.

How do you implement prop type checking?

Prop types can be checked using TypeScript or runtime validation. Define interfaces for props. Implement validation in onMount or initialization. Handle type errors appropriately.

How do you handle async props?

Async props can be handled using promises or async/await. Handle loading states. Use reactive statements for async updates. Manage error states for async props.

What are computed props?

Computed props derive values from other props using reactive declarations. Example: $: fullName = `${firstName} ${lastName}`. Update automatically when dependencies change.

How do you implement prop watchers?

Prop watchers use reactive statements to observe changes. Can trigger side effects or validations. Handle prop updates asynchronously. Support complex watch conditions.

How do you handle prop defaults?

Prop defaults are set in export statement or computed. Consider component initialization. Handle undefined values. Support dynamic defaults. Validate default values.

What are event modifiers?

Event modifiers customize event behavior. Include preventDefault, stopPropagation, once, capture. Used with on: directive. Example: on:click|preventDefault. Support multiple modifiers.

How do you implement prop transformation?

Prop transformation converts prop values before use. Use computed properties or methods. Handle data formatting. Support bi-directional transformation. Validate transformed values.

What are dynamic event handlers?

Dynamic event handlers change based on props or state. Use computed values for handlers. Support conditional events. Handle dynamic binding. Manage handler lifecycle.

How do you implement prop persistence?

Prop persistence saves prop values between renders. Use stores or local storage. Handle persistence lifecycle. Support value restoration. Manage persistence errors.

What are compound components?

Compound components share state through context. Implement parent-child communication. Handle component composition. Support flexible APIs. Manage shared state.

How do you handle errors in lifecycle methods?

Error handling uses try/catch blocks or error boundaries. Handle async errors appropriately. Implement error recovery strategies. Support error reporting.

How do you manage state initialization in lifecycle methods?

State initialization happens in component creation or onMount. Handle async initialization. Support loading states. Implement initialization strategies.

How do lifecycle methods interact with stores?

Store subscriptions are typically set up in onMount and cleaned in onDestroy. Handle store updates. Support auto-subscription. Manage subscription lifecycle.

How do you handle DOM measurements in lifecycle methods?

DOM measurements use afterUpdate for accurate values. Cache measurements when needed. Handle resize events. Support responsive measurements.

How do you implement initialization patterns?

Initialization patterns include lazy loading, conditional initialization, and dependency injection. Handle initialization order. Support async initialization.

How do you handle prop changes in lifecycle methods?

Prop changes trigger beforeUpdate and afterUpdate. Implement prop watchers. Handle derived values. Support prop validation in lifecycle.

How do you manage side effects in lifecycle methods?

Side effects management includes cleanup, ordering, and dependencies. Handle async side effects. Support cancellation. Implement side effect tracking.

How do lifecycle methods work with animations?

Animations interact with beforeUpdate and afterUpdate. Handle transition states. Support animation cleanup. Implement animation queuing.

How do you implement lifecycle hooks?

Lifecycle hooks extend default lifecycle behavior. Implement custom hooks. Support hook composition. Handle hook dependencies.

How do you handle component transitions?

Component transitions use lifecycle methods for coordination. Handle mount/unmount animations. Support transition states. Implement transition hooks.

How do you implement event debouncing?

Event debouncing delays handler execution. Use timer to postpone execution. Clear previous timer on new events. Example: implement custom action or store for debouncing.

How do you implement event throttling?

Event throttling limits execution frequency. Implement using timer and last execution time. Ensure minimum time between executions. Support custom throttle intervals.

How do you handle keyboard events?

Keyboard events use on:keydown, on:keyup, on:keypress. Access key information through event.key. Support key combinations. Handle keyboard navigation.

How do you handle drag and drop events?

Drag and drop uses dragstart, dragover, drop events. Set draggable attribute. Handle data transfer. Support drag visualization. Implement drop zones.

How do you handle form events?

Form events include submit, reset, change. Prevent default submission. Handle validation. Collect form data. Support dynamic forms.

How do you implement custom event modifiers?

Custom modifiers use actions (use:). Implement modifier logic. Support parameters. Handle cleanup. Share across components.

How do you handle outside clicks?

Outside clicks check event.target relationship. Implement using actions. Handle document clicks. Support multiple elements. Clean up listeners.

How do you handle touch events?

Touch events include touchstart, touchmove, touchend. Handle gestures. Support multi-touch. Implement touch feedback. Handle touch coordinates.

How do you handle scroll events?

Scroll events track scroll position. Implement scroll handlers. Support infinite scroll. Handle scroll optimization. Manage scroll restoration.

How do you handle window events?

Window events use svelte:window component. Listen to resize, scroll, online/offline. Handle cleanup. Support event parameters.

How do you implement custom stores?

Custom stores implement subscribe method. Can add custom methods. Handle internal state. Example: function createCustomStore() { const { subscribe, set } = writable(0); return { subscribe, increment: () => update(n => n + 1) }; }

How do you handle async stores?

Async stores handle asynchronous data. Support loading states. Handle errors. Example: const data = writable(null); async function fetchData() { const response = await fetch(url); data.set(await response.json()); }

How do you implement store persistence?

Store persistence saves state to storage. Implement auto-save. Handle state rehydration. Example: Subscribe to changes and save to localStorage. Load initial state from storage.

How do you handle store dependencies?

Store dependencies use derived stores or reactive statements. Handle update order. Manage circular dependencies. Support dependency tracking.

How do you implement store middleware?

Store middleware intercepts store operations. Implement custom behaviors. Handle side effects. Example: Create wrapper store with logging or validation.

How do you handle store errors?

Store error handling catches and processes errors. Implement error states. Support error recovery. Example: Try-catch in store operations, maintain error state.

How do you implement store validation?

Store validation ensures valid state. Implement validation rules. Handle validation errors. Example: Create wrapper store that validates updates.

How do you optimize store updates?

Store optimization includes batching updates, debouncing, throttling. Handle performance bottlenecks. Example: Implement update batching or debounced updates.

How do you implement store composition?

Store composition combines multiple stores. Create higher-order stores. Handle store relationships. Example: Combine multiple stores into single interface.

How do you manage store lifecycles?

Store lifecycle management handles initialization, updates, cleanup. Support store creation/destruction. Example: Implement cleanup in onDestroy, handle store initialization.

How do you create custom transitions?

Custom transitions are functions returning animation parameters. Include css and tick functions. Handle enter/exit animations. Support custom parameters.

How do you handle transition events?

Transition events include introstart, introend, outrostart, outroend. Listen using on: directive. Example: <div transition:fade on:introend={handleEnd}>.

What are CSS animations in Svelte?

CSS animations use standard CSS animation properties. Can be combined with transitions. Example: <div animate:flip>. Support keyframes and animation properties.

How do you use the flip animation?

Flip animation smoothly animates layout changes. Example: <div animate:flip>. Parameters include duration, delay. Useful for list reordering.

How do you handle multiple transitions?

Multiple transitions can be combined using different directives. Handle timing coordination. Support transition groups. Manage transition order.

How do you implement spring animations?

Spring animations use spring() function. Handle physics-based animations. Support stiffness and damping. Example: spring(value, {stiffness: 0.3}).

How do you handle transition crossfade?

Crossfade creates smooth transitions between elements. Use crossfade() function. Handle element replacement. Support key-based transitions.

How do you optimize transition performance?

Optimize using CSS transforms, will-change property. Handle hardware acceleration. Manage animation frame rate. Monitor performance metrics.

How do you handle transition groups?

Transition groups coordinate multiple transitions. Handle group timing. Support synchronized animations. Manage group lifecycle.

How do you implement deferred transitions?

Deferred transitions delay animation start. Handle transition timing. Support conditional transitions. Manage transition state.

How do you implement conditional slots?

Conditional slots use if blocks around slots. Handle slot presence checks. Support dynamic slot selection. Example: {#if condition}<slot></slot>{/if}

How do you handle dynamic slot names?

Dynamic slot names use computed values. Support runtime slot selection. Handle dynamic content projection. Example: <slot name={dynamicName}>

How do you implement slot validation?

Slot validation checks content type and structure. Handle invalid content. Support content restrictions. Implement validation logic.

How do you handle slot events?

Slot events bubble through component hierarchy. Handle event forwarding. Support event modification. Manage event propagation.

How do you handle slot lifecycles?

Slot lifecycles manage content updates. Handle content mounting/unmounting. Support cleanup operations. Manage slot state.

How do you implement slot composition?

Slot composition combines multiple slots. Handle nested slots. Support slot inheritance. Implement composition patterns.

How do you optimize slot performance?

Slot optimization improves rendering efficiency. Handle content caching. Support lazy loading. Manage update frequency.

How do you handle slot error boundaries?

Error boundaries catch slot content errors. Handle error recovery. Support fallback content. Manage error state.

How do you implement conditional slots?

Conditional slots use if blocks around slots. Handle slot presence checks. Support dynamic slot selection. Example: {#if condition}<slot></slot>{/if}

How do you handle dynamic slot names?

Dynamic slot names use computed values. Support runtime slot selection. Handle dynamic content projection. Example: <slot name={dynamicName}>

How do you implement slot validation?

Slot validation checks content type and structure. Handle invalid content. Support content restrictions. Implement validation logic.

How do you handle slot events?

Slot events bubble through component hierarchy. Handle event forwarding. Support event modification. Manage event propagation.

How do you implement slot middleware?

Slot middleware processes slot content. Handle content transformation. Support content filtering. Implement middleware chain.

How do you handle slot lifecycles?

Slot lifecycles manage content updates. Handle content mounting/unmounting. Support cleanup operations. Manage slot state.

How do you implement slot composition?

Slot composition combines multiple slots. Handle nested slots. Support slot inheritance. Implement composition patterns.

How do you optimize slot performance?

Slot optimization improves rendering efficiency. Handle content caching. Support lazy loading. Manage update frequency.

How do you handle slot error boundaries?

Error boundaries catch slot content errors. Handle error recovery. Support fallback content. Manage error state.

How do you implement route guards?

Route guards protect routes using load functions. Check authentication/authorization. Return redirect for unauthorized access. Support async checks.

How do you handle nested layouts?

Nested layouts use multiple +layout.svelte files. Each level adds layout. Support layout inheritance. Handle layout data. Share layout between routes.

How do you implement route preloading?

Preloading uses data-sveltekit-preload attribute. Fetches data before navigation. Support hover preloading. Handle preload strategies. Optimize performance.

How do you handle route transitions?

Route transitions use page transitions API. Support enter/leave animations. Handle transition lifecycle. Implement custom transitions. Manage transition state.

How do you implement route middleware?

Route middleware uses hooks.server.js file. Handle request/response. Support authentication. Implement custom logic. Manage middleware chain.

How do you handle route caching?

Route caching implements caching strategies. Handle data caching. Support page caching. Implement cache invalidation. Manage cache lifecycle.

How do you implement route validation?

Route validation handles parameter validation. Support request validation. Implement validation rules. Handle validation errors. Manage validation state.

How do you handle route state?

Route state management uses stores or context. Handle state persistence. Support state sharing. Implement state updates. Manage state lifecycle.

How do you optimize route performance?

Route optimization includes code splitting, preloading. Handle lazy loading. Support route prioritization. Implement performance monitoring.

How do you implement context patterns?

Context patterns include provider components, dependency injection, service locator. Handle context composition. Support context inheritance. Implement context strategies.

How do you handle context updates?

Context updates require component reinitialization. Can combine with stores for reactive updates. Handle update propagation. Manage update lifecycle.

How do you handle context dependencies?

Context dependencies manage relationships between contexts. Handle dependency order. Support circular dependencies. Implement dependency resolution.

How do you implement context composition?

Context composition combines multiple contexts. Handle context merging. Support context inheritance. Implement composition patterns.

How do you handle context initialization?

Context initialization sets up initial context state. Handle async initialization. Support initialization order. Implement initialization strategies.

How do you implement context middleware?

Context middleware processes context operations. Handle context transformation. Support middleware chain. Implement middleware patterns.

How do you handle context errors?

Context error handling manages error states. Handle missing context. Support error recovery. Implement error boundaries.

How do you optimize context usage?

Context optimization improves performance. Handle context caching. Support selective updates. Implement optimization strategies.

How do you handle context cleanup?

Context cleanup manages resource disposal. Handle cleanup order. Support cleanup hooks. Implement cleanup strategies.

How do you implement custom actions?

Custom actions are functions returning optional destroy method. Handle DOM node manipulation. Support parameters. Example: use:customAction={params}.

How do you handle binding validation?

Binding validation ensures valid values. Handle input constraints. Support custom validation. Implement error handling. Manage validation state.

How do you implement binding middleware?

Binding middleware processes binding operations. Handle value transformation. Support validation chain. Implement middleware pattern.

How do you handle binding dependencies?

Binding dependencies manage related bindings. Handle dependency updates. Support dependency tracking. Implement dependency resolution.

How do you optimize binding performance?

Binding optimization improves update efficiency. Handle update batching. Support selective updates. Implement performance monitoring.

How do you implement custom directives?

Custom directives extend element functionality. Handle directive lifecycle. Support directive parameters. Implement cleanup methods.

How do you handle binding errors?

Binding error handling manages invalid states. Handle error recovery. Support error notifications. Implement error boundaries.

How do you implement binding composition?

Binding composition combines multiple bindings. Handle binding interaction. Support binding inheritance. Implement composition patterns.

How do you handle binding cleanup?

Binding cleanup manages resource disposal. Handle cleanup order. Support cleanup hooks. Implement cleanup strategies.

How do you implement SSR data fetching?

SSR data fetching uses load functions. Handle async operations. Support caching strategies. Implement error handling. Manage data dependencies.

How do you handle SSR caching?

SSR caching implements cache strategies. Handle cache invalidation. Support cache headers. Implement cache storage. Manage cache lifecycle.

How do you optimize SSR performance?

SSR optimization includes code splitting, caching, streaming. Handle resource optimization. Support performance monitoring. Implement optimization strategies.

How do you handle SSR session state?

SSR session state manages user sessions. Handle session storage. Support session persistence. Implement session security. Manage session lifecycle.

How do you implement SSR middleware?

SSR middleware processes server requests. Handle request transformation. Support middleware chain. Implement middleware patterns. Manage middleware order.

How do you handle SSR authentication?

SSR authentication manages user auth state. Handle auth flows. Support session management. Implement auth strategies. Manage auth security.

How do you implement SSR routing?

SSR routing handles server-side navigation. Handle route matching. Support dynamic routes. Implement routing strategies. Manage route state.

How do you handle SSR headers?

SSR headers manage HTTP headers. Handle cache control. Support content types. Implement header strategies. Manage header security.

How do you implement SSR forms?

SSR forms handle form submissions server-side. Handle form validation. Support file uploads. Implement CSRF protection. Manage form state.

How do you implement integration testing?

Integration testing verifies component interaction. Test multiple components. Handle data flow. Implement test scenarios. Manage test environment.

How do you test stores?

Store testing verifies store behavior. Test store updates. Handle subscriptions. Implement store mock. Manage store state.

How do you implement test mocks?

Test mocks simulate dependencies. Handle external services. Support mock responses. Implement mock behavior. Manage mock state.

How do you test routing?

Route testing verifies navigation behavior. Test route parameters. Handle route changes. Implement navigation tests. Manage route state.

How do you handle test fixtures?

Test fixtures provide test data. Handle data setup. Support test isolation. Implement fixture management. Manage fixture cleanup.

How do you test animations?

Animation testing verifies transition behavior. Test animation states. Handle animation timing. Implement animation checks. Manage animation events.

How do you implement test hooks?

Test hooks handle test lifecycle. Support setup/teardown. Implement test utilities. Manage test state. Handle test dependencies.

How do you test error handling?

Error handling testing verifies error states. Test error boundaries. Handle error recovery. Implement error scenarios. Manage error logging.

How do you handle test coverage?

Test coverage tracks code coverage. Generate coverage reports. Set coverage targets. Implement coverage checks. Manage coverage gaps.

How do you implement test organization?

Test organization structures test files. Group related tests. Support test discovery. Implement naming conventions. Manage test hierarchy.

How do you implement caching strategies?

Caching strategies include browser cache, service workers, SSR cache. Handle cache invalidation. Support offline functionality. Implement cache policies.

How do you optimize animations?

Animation optimization includes using CSS animations when possible, hardware acceleration, efficient transitions. Handle animation timing. Minimize reflows.

How do you handle large lists?

Large list optimization includes virtual scrolling, pagination, infinite scroll. Use keyed each blocks. Implement list chunking. Handle DOM recycling.

How do you optimize image loading?

Image optimization includes lazy loading, responsive images, proper formats. Use srcset attribute. Implement placeholder images. Handle image compression.

How do you implement performance monitoring?

Performance monitoring tracks metrics like load time, FCP, TTI. Use browser DevTools. Implement analytics. Handle performance reporting.

How do you optimize SSR performance?

SSR optimization includes caching, streaming, efficient data loading. Handle server resources. Implement response compression. Optimize render time.

How do you handle resource prioritization?

Resource prioritization includes critical CSS, script loading strategies, preload/prefetch. Handle resource order. Implement loading priorities.

How do you optimize build configuration?

Build optimization includes proper Vite/Rollup config, production settings, environment optimization. Handle build process. Implement build strategies.

How do you handle performance testing?

Performance testing measures load time, interaction time, resource usage. Implement benchmarks. Handle performance metrics. Support performance monitoring.

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Svelte Interview Questions Your Guide to Success

svelte

How do you implement two-way binding in Svelte?

How do you handle component initialization logic?

What are derived stores in Svelte?

How do you implement dynamic component loading?

What are actions in Svelte?

How do you handle component composition patterns?

What is the purpose of reactive statements?

How do you implement component interfaces?

What are component lifecycle methods?

How do you handle component state persistence?

How do you implement derived stores?

How do you handle async derived stores?

How do you implement custom stores?

How do you handle store initialization?

How do you implement store persistence?

How do you handle store subscriptions cleanup?

How do you handle store error states?

How do you implement store middleware?

How do you implement prop type checking?

How do you handle async props?

What are computed props?

How do you implement prop watchers?

How do you handle prop defaults?

What are event modifiers?

How do you implement prop transformation?

What are dynamic event handlers?

How do you implement prop persistence?

What are compound components?

How do you handle errors in lifecycle methods?

How do you manage state initialization in lifecycle methods?

How do lifecycle methods interact with stores?

How do you handle DOM measurements in lifecycle methods?

How do you implement initialization patterns?

How do you handle prop changes in lifecycle methods?

How do you manage side effects in lifecycle methods?

How do lifecycle methods work with animations?

How do you implement lifecycle hooks?

How do you handle component transitions?

How do you implement event debouncing?

How do you implement event throttling?

How do you handle keyboard events?

How do you handle drag and drop events?

How do you handle form events?

How do you implement custom event modifiers?

How do you handle outside clicks?

How do you handle touch events?

How do you handle scroll events?

How do you handle window events?

How do you implement custom stores?

How do you handle async stores?

How do you implement store persistence?

How do you handle store dependencies?

How do you implement store middleware?

How do you handle store errors?

How do you implement store validation?

How do you optimize store updates?

How do you implement store composition?

How do you manage store lifecycles?

How do you create custom transitions?

How do you handle transition events?

What are CSS animations in Svelte?

How do you use the flip animation?

How do you handle multiple transitions?

How do you implement spring animations?

How do you handle transition crossfade?

How do you optimize transition performance?

How do you handle transition groups?

How do you implement deferred transitions?

How do you implement conditional slots?

How do you handle dynamic slot names?

How do you implement slot validation?

How do you handle slot events?