Transitions & Animations Interview Questions

Transitions in Svelte are built-in animations that play when elements are added to or removed from the DOM. They are added using the transition: directive, with built-in functions like fade, fly, slide, etc.

Fade transition is used with transition:fade directive. Example: <div transition:fade>. Can accept parameters like duration and delay. Animates opacity from 0 to 1 or vice versa.

in: and out: directives specify different transitions for entering and leaving. Example: <div in:fade out:fly>. Allows different animations for element addition and removal.

Transition parameters customize animation behavior. Example: transition:fade={{duration: 300, delay: 100}}. Include properties like duration, delay, easing function.

Fly transition animates position and opacity. Example: <div transition:fly={{y: 200}}>. Parameters include x, y coordinates, duration, opacity settings.

Slide transition animates element height. Example: <div transition:slide>. Useful for collapsible content. Can customize duration and easing.

Easing functions define animation progression. Import from svelte/easing. Example: transition:fade={{easing: quintOut}}. Affects animation timing and feel.

transition:local restricts transitions to when parent component is added/removed. Prevents transitions during internal state changes. Example: <div transition:fade|local>.

Scale transition animates size and opacity. Example: <div transition:scale>. Parameters include start, opacity, duration. Useful for pop-in effects.

Draw transition animates SVG paths. Example: <path transition:draw>. Parameters include duration, delay, easing. Useful for path animations.

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

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

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

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

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

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

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

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

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

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

Complex sequences combine multiple animations. Handle timing coordination. Support sequential and parallel animations. Manage animation state.

Animation middleware intercepts and modifies animations. Handle animation pipeline. Support middleware chain. Manage animation flow.

Animation state machines manage complex animation states. Handle state transitions. Support parallel states. Manage animation logic.

Animation presets define reusable animations. Handle preset parameters. Support preset composition. Manage preset library.

Animation testing verifies animation behavior. Handle timing tests. Support visual regression. Manage test assertions.

Animation debugging tracks animation state. Handle debugging tools. Support timeline inspection. Manage debug output.

Animation optimization improves performance. Handle frame rate. Support GPU acceleration. Manage rendering pipeline.

Animation documentation describes animation behavior. Generate documentation automatically. Support example animations. Manage documentation updates.

Animation monitoring tracks animation performance. Handle metrics collection. Support performance analysis. Manage monitoring data.