Challenge Library
Coding Challenges
5,893 curated questions across every arena — browse by topic, then jump into a live 3-minute battle to put them to the test.
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101 challenges matching your filters
Clear topic filter- Multiple ChoiceHard
aria-live
frontendhard - Multiple ChoiceHard
Accessible names
frontendhard - Code AnalysisHard
Trace: Debounce vs Throttle
frontendanalysishard - Code AnalysisHard
Trace: Responsive Grid
frontendanalysishard - Multiple ChoiceHard
IndexedDB
frontendhard - Multiple ChoiceHard
ResizeObserver
frontendhard - Multiple ChoiceHard
Broadcast Channel
frontendhard - Multiple ChoiceHard
ITCSS
frontendhard - Multiple ChoiceHard
OOCSS
frontendhard - Multiple ChoiceHard
SMACSS
frontendhard - Multiple ChoiceHard
Critical CSS extraction
frontendhard - Multiple ChoiceHard
Compound components
frontendhard - Multiple ChoiceHard
Ref forwarding
frontendhard - Multiple ChoiceHard
Render optimization
frontendhard - Code AnalysisHard
Transform performance
frontendhard - Code AnalysisHard
Layer priority
frontendhard - Code AnalysisHard
Opacity click
frontendhard - Code AnalysisHard
will-change hint
frontendhard - Multiple ChoiceHard
@layer
frontendhard - Multiple ChoiceHard
Initial/inherit/unset
frontendhard - Multiple ChoiceHard
will-change
frontendhard - Multiple ChoiceHard
clip-path
frontendhard - Multiple ChoiceHard
Shadow DOM
frontendhard - Multiple ChoiceHard
MutationObserver
frontendhard - Multiple ChoiceHard
IntersectionObserver
frontendhard - Multiple ChoiceHard
Custom events — dispatchEvent
frontendhard - Multiple ChoiceHard
Passive event listeners
frontendhard - Multiple ChoiceHard
AbortController
frontendhard - Multiple ChoiceHard
Browser rendering
frontendhard - Multiple ChoiceHard
CSS isolation
frontendhard - Multiple ChoiceHard
CSS backdrop-filter
frontendhard - Multiple ChoiceHard
CSS containment
frontendhard - Multiple ChoiceHard
CSS shape-outside
frontendhard - Multiple ChoiceHard
View Transitions API
frontendhard - Multiple ChoiceHard
useDeferredValue
frontendhard - Multiple ChoiceHard
CSS overscroll-behavior
frontendhard - Multiple ChoiceHard
Import maps
frontendhard - Multiple ChoiceHard
CSS text-wrap balance
frontendhard - Multiple ChoiceHard
Web Locks API
frontendhard - Multiple ChoiceHard
CSS nesting
frontendhard - Multiple ChoiceHard
Scroll-driven animations
frontendhard - Multiple ChoiceHard
CSS :has() selector
frontendhard - Multiple ChoiceHard
Popover API
frontendhard - Multiple ChoiceHard
CSS anchor positioning
frontendhard - Multiple ChoiceHard
Declarative Shadow DOM
frontendhard - Multiple ChoiceHard
CSS font-palette
frontendhard - Multiple ChoiceHard
Navigation API
frontendhard - Multiple ChoiceHard
Fetch Priority API
frontendhard - Multiple ChoiceHard
Storage API estimate
frontendhard - Multiple ChoiceHard
CSS layer specificity
frontendhard - Multiple ChoiceHard
CSS color-mix
frontendhard - Multiple ChoiceHard
CSS container style queries
frontendhard - Code AnalysisHard
Object.keys order
frontendhard - Code AnalysisHard
Promise.resolve unwrap
frontendhard - Code AnalysisHard
Object.seal delete
frontendhard - Code AnalysisHard
String substring
frontendhard - Code AnalysisHard
String codePointAt
frontendhard - Code AnalysisHard
CSS counters
frontendhard - Code AnalysisHard
Reduce empty no init
frontendhard - Code AnalysisHard
useLayoutEffect
frontendhard
Practice now, dominate the arena
Every challenge here is drawn from the live Code Royale pool. Review a question, then head to the arena to answer under pressure against a real opponent — 3-minute matches, Elo ranking, and badge tiers on the line.