Practice problems

Browse 508 theory questions and coding exercises. Filter by lesson, type or difficulty to choose what to practice.

Completion marks record your own progress, not an automatically checked result.


Medium	Virtual DOM	Theory
Medium	Hash Tables	Coding
Medium	Numbers	Coding
Hard	Micro-frontends	Theory
Medium	Arrays	Coding
Medium	Hash Tables	Coding
Easy	Data Types	Theory
Easy	Component Architecture	Theory
Hard	Data Types	Coding
Medium	Component Architecture	Theory
Medium	Trees	Coding
Medium	Virtual DOM	Theory
Medium	Strings	Coding
Medium	Scope & Hoisting	Theory
Medium	Graphs	Coding
Medium	Type Coercion	Theory
Medium	Arrays	Coding
Medium	Graphs	Coding
Medium	Virtual DOM	Theory
Easy	Stacks	Coding
Easy	Data Types	Theory
Medium	Trees	Coding
Easy	Bloom Filters	Coding
Easy	Remaining Primitives	Coding
Easy	Function Types	Theory
Easy	Hash Tables	Coding
Hard	Reconciliation	Theory
Medium	Tries	Coding
Medium	Migration strategies	Theory
Medium	Matrix Traversal	Coding
Medium	CORS	Theory
Hard	Tries	Coding
Easy	Testing Strategies	Theory
Medium	Minimum Spanning Trees	Coding
Medium	Closures	Theory
Hard	K-way Merge	Coding
Medium	this & Binding	Theory
Easy	State Management	Theory
Medium	Testing Strategies	Theory
Medium	Heaps	Coding
Hard	this & Binding	Theory
Medium	Sorting Techniques	Coding
Medium	Sliding Window	Coding
Medium	Type Guards	Theory
Medium	Sliding Window	Coding
Medium	Fast and Slow Pointers	Coding
Hard	this & Binding	Coding
Medium	Scope Chain	Theory
Medium	Scope Chain	Theory
Medium	Merge Intervals	Coding
Medium	Type Coercion	Theory
Medium	Code Splitting	Theory
Medium	Bit Manipulation	Coding
Medium	Prototypes	Theory
Medium	Union Find	Coding
Easy	Cyclic Sort	Coding
Medium	Prototypes	Theory
Medium	Objects and Classes	Theory
Medium	Fast and Slow Pointers	Coding
Easy	Error Handling	Theory
Medium	Error Handling	Theory
Medium	Graphs	Coding
Medium	Two Pointers	Coding
Medium	Combinatorial Optimization	Coding
Medium	Modules	Theory
Hard	Convex Hull	Coding
Medium	Function Types	Theory
Easy	Reconciliation	Theory
Medium	Linked List Reversal	Coding
Medium	Matrix Traversal	Coding
Medium	Tree BFS	Coding
Medium	Function Types	Theory
Medium	Closures	Theory
Medium	Server-Side Rendering	Theory
Easy	Performance	Theory
Easy	Engine & Runtime	Theory
Easy	Two Pointers	Coding
Easy	Accessibility	Theory
Medium	Top K Elements	Coding
Medium	Subsets	Coding
Medium	Context & Call Stack	Theory
Medium	Subsets	Coding
Easy	Deployment	Theory
Medium	Linked Lists	Coding
Medium	Context & Call Stack	Theory
Medium	Subsets	Coding
Easy	TS Basics	Theory
Medium	Accessibility	Theory
Easy	Event Loop	Theory
Hard	Sorting Techniques	Coding
Hard	Frontend Interviews	Theory
Easy	Event Loop	Theory
Easy	Asynchronous JavaScript	Theory
Medium	Recursion and Memoization	Coding
Hard	Dynamic Programming	Coding
Easy	Asynchronous JavaScript	Theory
Easy	Memory Management	Theory
Medium	Objects and Classes	Theory
Medium	Frontend Interviews	Theory
Medium	Binary Search	Coding
Medium	Memory Management	Theory
Medium	Graphs	Coding
Easy	TS Basics	Theory
Medium	Data Types	Theory
Medium	Symbols	Theory
Hard	TS Basics	Theory
Medium	Objects and Classes	Theory
Medium	Queues	Coding
Easy	Sorting Techniques	Coding
Medium	Top K Elements	Coding
Medium	Error Handling	Theory
Medium	Deployment	Theory
Medium	Basic Types	Theory
Hard	Conditional Types	Theory
Easy	Sets	Coding
Easy	Basic Types	Theory
Medium	Git	Theory
Hard	Suffix Arrays and Suffix Trees	Coding
Medium	Sliding Window	Coding
Medium	Engine & Runtime	Theory
Medium	Engine & Runtime	Theory
Easy	Git	Theory
Medium	State Management	Theory
Medium	K-way Merge	Coding
Hard	K-way Merge	Coding
Easy	Scope & Hoisting	Theory
Easy	Two Pointers	Coding
Medium	Graph DFS	Coding
Medium	Topological Sort	Coding
Easy	Top K Elements	Coding
Hard	Enums	Theory
Easy	Tree BFS	Coding
Medium	State Management	Theory
Easy	Tree DFS	Coding
Medium	Functional Programming	Coding
Hard	Two Heaps	Coding
Medium	Enums	Theory
Easy	Scope Chain	Theory
Medium	Advanced Types	Theory
Hard	Binary Search	Coding
Easy	Interfaces	Theory
Easy	Prototypes	Theory
Easy	Basic Types	Theory
Easy	Basic Types	Theory
Medium	Conditional Types	Theory
Easy	CI/CD	Theory
Medium	Topological Sort	Coding
Hard	Advanced Types	Theory
Easy	Enums	Theory
Medium	Generics	Theory
Medium	Generics	Theory
Easy	Advanced Types	Theory
Easy	CI/CD	Theory
Hard	Topological Sort	Coding
Medium	Utility Types	Theory
Medium	Type Guards	Theory
Medium	Declarations	Theory
Medium	Recursion and Memoization	Coding
Medium	Backtracking	Coding
Medium	Greedy Algorithms	Coding
Hard	Decorators	Theory
Easy	Type-level Programming	Theory
Medium	Type-level Programming	Theory
Medium	CI/CD	Theory
Medium	Union Find	Coding
Medium	Shortest Path Algorithms	Coding
Easy	Project Configuration	Theory
Easy	Maps	Coding
Easy	Namespaces and Modules	Theory
Hard	Merge Intervals	Coding
Hard	Type Inference	Theory
Medium	Randomized Algorithms	Coding
Medium	Event Loop	Theory
Medium	Higher-Order Functions	Theory
Hard	Approximation Algorithms	Coding
Medium	Component Architecture	Theory
Hard	Approximation Algorithms	Coding
Hard	Reconciliation	Theory
Hard	Network Flow Algorithms	Coding
Medium	Web APIs	Theory
Easy	Virtual DOM	Theory
Medium	Combinatorial Optimization	Coding
Medium	Tree BFS	Coding
Medium	Conditional Types	Theory
Medium	Longest Common Substring	Coding
Easy	Longest Common Substring	Coding
Medium	CORS	Theory
Hard	Frontend Interviews	Coding
Medium	Code Splitting	Theory
Medium	Frontend Interviews	Theory
Medium	Web APIs	Theory
Easy	Build Tools	Theory
Medium	Build Tools	Theory
Medium	Build Tools	Theory
Easy	Performance	Theory
Medium	Micro-frontends	Theory
Hard	Micro-frontends	Theory
Easy	Frontend Interviews	Theory
Medium	CORS	Theory
Hard	Server-Side Rendering	Theory
Medium	Graph DFS	Coding
Easy	Accessibility	Theory
Easy	Data Types	Theory
Hard	Asynchronous JavaScript	Coding
Medium	Frontend Interviews	Theory
Medium	Deployment	Theory
Easy	Code Splitting	Theory
Medium	Deployment	Theory
Medium	Deployment	Theory
Medium	CI/CD	Theory
Medium	Memory Management	Theory
Medium	Memory Management	Theory
Medium	Git	Theory
Medium	CI/CD	Theory
Medium	Promise Patterns	Theory
Medium	Data Types	Theory
Easy	Functional Programming	Theory
Easy	Functional Programming	Theory
Easy	Higher-Order Functions	Theory
Easy	Higher-Order Functions	Theory
Medium	Promise Patterns	Theory
Medium	Async/Await	Theory
Easy	Generators	Theory
Medium	Type Coercion	Theory
Easy	Type Coercion	Theory
Hard	Functional Programming	Coding
Easy	Generators	Coding
Easy	Symbols	Theory
Medium	TS Basics	Theory
Medium	Longest Common Substring	Coding
Easy	Meta-programming	Theory
Easy	Meta-programming	Coding
Easy	Service Workers	Theory
Hard	Browser Storage	Coding
Easy	Service Workers	Theory
Medium	State Management	Theory
Medium	Memory Leaks	Theory
Easy	Web Workers	Theory
Medium	Web Workers	Theory
Hard	Performance Optimization	Coding
Medium	Basic Types	Theory
Easy	Performance Optimization	Theory
Medium	Performance Optimization	Theory
Easy	Browser Storage	Theory
Easy	Design Patterns	Theory
Medium	Browser Security	Theory
Easy	Design Patterns	Theory
Easy	Scope & Hoisting	Theory
Easy	Closures	Theory
Medium	Prototypes	Theory
Medium	Interfaces	Theory
Medium	Reflection	Theory
Medium	Reflection	Theory
Hard	Higher-Order Functions	Coding
Medium	Interfaces	Theory
Easy	Generics	Theory
Medium	Generics	Theory
Hard	Tree DFS	Coding
Easy	Scope Chain	Theory
Medium	Interfaces	Theory
Medium	Enums	Theory
Easy	Generics	Theory
Medium	Palindromic Subsequence	Coding
Medium	Utility Types	Theory
Easy	Maps	Coding
Easy	Error Handling	Theory
Hard	Promise Patterns	Coding
Medium	Stacks	Coding
Hard	Promise Patterns	Theory
Medium	Engine & Runtime	Theory
Medium	Advanced Types	Theory
Hard	Longest Common Substring	Coding
Hard	Async/Await	Coding
Medium	Context & Call Stack	Theory
Medium	Objects	Coding
Medium	Tries	Coding
Medium	Context & Call Stack	Theory
Easy	Generators	Theory
Easy	Generators	Theory
Medium	Conditional Types	Theory
Hard	Conditional Types	Theory
Easy	Generators	Theory
Medium	Heaps	Coding
Easy	Memory Management	Theory
Easy	Meta-programming	Theory
Medium	Linked List Reversal	Coding
Hard	Meta-programming	Coding
Medium	Graph BFS	Coding
Hard	Utility Types	Coding
Easy	Symbols	Theory
Medium	Binary Search	Coding
Easy	Symbols	Theory
Easy	Memory Leaks	Theory
Hard	Palindromic Subsequence	Coding
Medium	Utility Types	Coding
Medium	Type Guards	Theory
Medium	Dynamic Programming	Coding
Hard	Sqrt Decomposition	Coding
Medium	Utility Types	Theory
Medium	Memory Leaks	Theory
Hard	Backtracking	Coding
Medium	Declarations	Theory
Medium	Declarations	Theory
Medium	Dynamic Programming	Coding
Medium	Segment Trees	Coding
Medium	Type Guards	Theory
Easy	Type Guards	Theory
Easy	Web Workers	Theory
Hard	Segment Trees	Coding
Medium	Declarations	Theory
Easy	Declarations	Theory
Medium	Web Workers	Theory
Easy	this & Binding	Theory
Hard	Performance Optimization	Coding
Medium	this & Binding	Theory
Easy	Service Workers	Theory
Easy	Type Coercion	Theory
Hard	Decorators	Theory
Easy	Browser Storage	Theory
Easy	Error Handling	Theory
Hard	Decorators	Theory
Medium	Event Handling	Theory
Medium	Function Types	Theory
Medium	Event Handling	Theory
Medium	Event Handling	Theory
Easy	Event Handling	Theory
Hard	Decorators	Theory
Medium	Event Handling	Theory
Hard	Stacks	Coding
Easy	Asynchronous JavaScript	Theory
Easy	Browser Security	Theory
Medium	Browser Security	Theory
Easy	Enums	Theory
Hard	Code Splitting	Theory
Easy	Design Patterns	Theory
Medium	Web Application Security	Theory
Medium	Testing Strategies	Theory
Medium	Function Types	Theory
Hard	Decorators	Coding
Medium	Design Patterns	Coding
Medium	Compiler	Theory
Medium	Maximum Flow	Coding
Easy	Migration strategies	Theory
Medium	Reflection	Theory
Medium	Suffix Arrays and Suffix Trees	Coding
Hard	Type Coercion	Coding
Medium	Namespaces and Modules	Theory
Easy	Reflection	Theory
Medium	Strings	Coding
Medium	Closures	Theory
Medium	Closures	Theory
Easy	Strings	Coding
Hard	Reflection	Coding
Medium	Namespaces and Modules	Theory
Easy	TS Basics	Theory
Medium	Modules	Theory
Medium	Modules	Theory
Medium	Strings	Coding
Medium	Objects and Classes	Theory
Easy	Numbers	Coding
Medium	Numbers	Coding
Medium	Numbers	Coding
Medium	Engine & Runtime	Theory
Medium	Scope & Hoisting	Theory
Easy	Arrays	Coding
Medium	Context & Call Stack	Theory
Medium	Project Configuration	Theory
Medium	Scope & Hoisting	Theory
Medium	Type-level Programming	Theory
Medium	Virtual DOM	Theory
Medium	Advanced Types	Theory
Medium	Compiler	Theory
Hard	Type Inference	Theory
Medium	Scope Chain	Theory
Medium	this & Binding	Theory
Easy	Objects	Coding
Hard	Type-level Programming	Theory
Medium	Testing Strategies	Theory
Hard	Server-Side Rendering	Theory
Medium	Web Application Security	Theory
Easy	Functional Programming	Theory
Medium	Event Loop	Theory
Medium	Asynchronous JavaScript	Theory
Easy	Accessibility	Theory
Easy	Memory Leaks	Theory
Hard	Web Application Security	Theory
Medium	Service Workers	Coding
Medium	Web Application Security	Theory
Easy	Browser Storage	Theory
Medium	Project Configuration	Theory
Easy	Objects and Classes	Theory
Medium	Prototypes	Theory
Easy	Objects	Coding
Easy	Modules	Theory
Easy	Modules	Theory
Medium	Event Loop	Theory
Easy	Sets	Coding
Easy	Migration strategies	Theory
Medium	Sets	Coding
Medium	Asynchronous JavaScript	Theory
Medium	Migration strategies	Theory
Medium	Interfaces	Theory
Hard	Namespaces and Modules	Theory
Easy	Sets	Coding
Medium	Compiler	Theory
Medium	Type Inference	Theory
Hard	Type Inference	Theory
Easy	Maps	Coding
Easy	Maps	Coding
Easy	Remaining Primitives	Coding
Medium	Linked Lists	Coding
Medium	Sorting Techniques	Coding
Medium	Cyclic Sort	Coding
Hard	Backtracking	Coding
Medium	Greedy Algorithms	Coding
Medium	Queues	Coding
Medium	Hash Tables	Coding
Easy	Trees	Coding
Medium	Trees	Coding
Medium	Trees	Coding
Medium	Heaps	Coding
Medium	Heaps	Coding
Medium	Tries	Coding
Medium	Sorting Techniques	Coding
Medium	Sliding Window	Coding
Easy	Fast and Slow Pointers	Coding
Medium	Merge Intervals	Coding
Hard	Cyclic Sort	Coding
Hard	Linked List Reversal	Coding
Medium	Tree DFS	Coding
Medium	Two Heaps	Coding
Hard	Two Heaps	Coding
Medium	Graph BFS	Coding
Medium	Graph BFS	Coding
Medium	Graph DFS	Coding
Medium	State Management	Theory
Medium	Matrix Traversal	Coding
Medium	Palindromic Subsequence	Coding
Hard	Type-level Programming	Theory
Easy	Recursion and Memoization	Coding
Medium	Bit Manipulation	Coding
Hard	Greedy Algorithms	Coding
Hard	Minimum Spanning Trees	Coding
Medium	Shortest Path Algorithms	Coding
Medium	Randomized Algorithms	Coding
Medium	Sqrt Decomposition	Coding
Medium	Compiler	Theory
Hard	Compiler	Theory
Easy	Project Configuration	Theory
Medium	Project Configuration	Theory
Medium	Migration strategies	Theory
Easy	Type Inference	Theory
Medium	Namespaces and Modules	Theory
Medium	Component Architecture	Theory
Medium	Component Architecture	Theory
Hard	Reconciliation	Theory
Hard	Reconciliation	Theory
Medium	Web APIs	Theory
Easy	Web APIs	Theory
Medium	Web APIs	Theory
Medium	CORS	Theory
Medium	CORS	Theory
Easy	Testing Strategies	Theory
Medium	Build Tools	Theory
Medium	Build Tools	Theory
Easy	Code Splitting	Theory
Medium	Micro-frontends	Theory
Medium	Micro-frontends	Theory
Medium	Server-Side Rendering	Theory
Easy	Server-Side Rendering	Theory
Medium	Performance	Theory
Easy	Performance	Theory
Medium	Performance	Theory
Medium	Accessibility	Theory
Medium	Web Application Security	Theory
Medium	Git	Theory
Easy	Git	Theory
Easy	Higher-Order Functions	Theory
Hard	Promise Patterns	Theory
Medium	Meta-programming	Theory
Hard	Promise Patterns	Coding
Medium	Async/Await	Theory
Medium	Async/Await	Theory
Medium	Async/Await	Theory
Hard	Async/Await	Coding
Medium	Memory Leaks	Theory
Easy	Web Workers	Theory
Hard	Service Workers	Theory
Easy	Performance Optimization	Theory
Hard	Symbols	Coding
Medium	Browser Storage	Theory
Medium	Browser Security	Theory
Easy	Browser Security	Theory
Hard	Design Patterns	Coding
Medium	Strings	Coding
Medium	Numbers	Coding
Medium	Arrays	Coding
Medium	Arrays	Coding
Medium	Remaining Primitives	Coding
Easy	Objects	Coding
Medium	Objects	Coding
Easy	Sets	Coding
Medium	Maps	Coding
Easy	Linked Lists	Coding
Medium	Linked Lists	Coding
Medium	Stacks	Coding
Easy	Queues	Coding
Medium	Queues	Coding