Challenge Library
Coding Challenges
5,893 curated questions across every arena — browse by topic, then jump into a live 2-minute battle to put them to the test.
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5,893 challenges total
- Code AnalysisIntermediate
Table scope attribute
frontendintermediate - Code AnalysisBeginner
Required validation
frontendbeginner - Code AnalysisHard
Empty sandbox
frontendhard - Code AnalysisIntermediate
Picture source choice
frontendintermediate - Code AnalysisIntermediate
Dialog show
frontendintermediate - Code AnalysisIntermediate
Lazy load trigger
frontendintermediate - Multiple ChoiceBeginner
DOCTYPE
frontendbeginner - Multiple ChoiceBeginner
Semantic HTML — Landmarks
frontendbeginner - Multiple ChoiceBeginner
Alt attribute
frontendbeginner - Multiple ChoiceIntermediate
Form input types
frontendintermediate - Multiple ChoiceBeginner
Meta viewport
frontendbeginner - Multiple ChoiceBeginner
Form methods
frontendbeginner - Multiple ChoiceBeginner
Label element
frontendbeginner - Multiple ChoiceIntermediate
Table semantics
frontendintermediate - Multiple ChoiceBeginner
Heading hierarchy
frontendbeginner - Multiple ChoiceIntermediate
iframe sandbox
frontendintermediate - Multiple ChoiceIntermediate
Data attributes
frontendintermediate - Multiple ChoiceBeginner
HTML entities
frontendbeginner - Multiple ChoiceHard
Web components
frontendhard - Multiple ChoiceIntermediate
Template element
frontendintermediate - Multiple ChoiceIntermediate
Dialog element
frontendintermediate - Multiple ChoiceIntermediate
Picture element
frontendintermediate - Multiple ChoiceIntermediate
Native lazy loading
frontendintermediate - Multiple ChoiceIntermediate
ARIA basics
frontendintermediate - Multiple ChoiceBeginner
Required attribute
frontendbeginner - Multiple ChoiceIntermediate
Figure element
frontendintermediate - Multiple ChoiceIntermediate
Details/Summary
frontendintermediate - Multiple ChoiceIntermediate
Progressive enhancement
frontendintermediate - Multiple ChoiceIntermediate
HTML landmarks
frontendintermediate - Multiple ChoiceBeginner
HTML5 layout
frontendbeginner - Code AnalysisBeginner
Flex Centering — Grid Fallback
frontendbeginner - Code AnalysisBeginner
Grid columns
frontendbeginner - Code AnalysisIntermediate
Grid areas
frontendintermediate - Code AnalysisIntermediate
Sticky trigger
frontendintermediate - Code AnalysisHard
Container query apply
frontendhard - Code AnalysisBeginner
Aspect ratio shape
frontendbeginner - Code AnalysisHard
clamp() result
frontendhard - Code AnalysisIntermediate
Grid auto-fill
frontendintermediate - Code AnalysisIntermediate
object-fit cover
frontendintermediate - Code AnalysisIntermediate
Scroll snap
frontendintermediate - Multiple ChoiceBeginner
Flexbox
frontendbeginner - Multiple ChoiceBeginner
flex-direction
frontendbeginner - Multiple ChoiceBeginner
flex-wrap
frontendbeginner - Multiple ChoiceIntermediate
justify-content
frontendintermediate - Multiple ChoiceIntermediate
align-items
frontendintermediate - Multiple ChoiceIntermediate
flex shorthand
frontendintermediate - Multiple ChoiceBeginner
CSS Grid
frontendbeginner - Multiple ChoiceIntermediate
grid-template
frontendintermediate - Multiple ChoiceIntermediate
fr unit
frontendintermediate - Multiple ChoiceIntermediate
grid-template-areas
frontendintermediate - Multiple ChoiceBeginner
gap property
frontendbeginner - Multiple ChoiceBeginner
Media queries
frontendbeginner - Multiple ChoiceIntermediate
Mobile-first
frontendintermediate - Multiple ChoiceIntermediate
position:sticky
frontendintermediate - Multiple ChoiceIntermediate
aspect-ratio
frontendintermediate - Multiple ChoiceIntermediate
object-fit
frontendintermediate - Multiple ChoiceHard
min/max/clamp
frontendhard - Multiple ChoiceHard
container queries (018)
frontendhard - Multiple ChoiceHard
Logical properties
frontendhard - Multiple ChoiceIntermediate
scroll-snap
frontendintermediate
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