Microsoft

Application that allows users to perform basic arithmetic operations, such as addition, subtraction, multiplication, and division.

Calculator

Build an interactive matching game where players pair countries with their capitals.

Country Capital Game

Build an NxN Tic Tac Toe game where the board size is configurable and winning lines are generated automatically for any board size.

NxN Tic Tac Toe

The tiny animations brings a lot of joy to the user experience. ✨

Spinner with CSS

Build an editable spreadsheet grid on top of a formula engine: edit a cell to see its formula, blur to see the value, and watch dependent cells update through event delegation and imperative DOM writes.

Spreadsheet UI

Build a 3x3 Tic Tac Toe board with alternating X and O turns, game status display, and a restart button.

Tic Tac Toe I

Add winner detection logic to the Tic Tac Toe game by checking rows, columns, and diagonals for three matching marks.

Tic Tac Toe II

Integrate async request handling into the Tic Tac Toe game to send game results to a server endpoint.

Tic Tac Toe III

Detect whether a function was invoked as a regular function call or as a constructor with the new keyword.

Check if Called with new

Given a DOM element, generate a unique CSS selector string that can be used to select that exact element from the document.

CSS Selector Generator

Design a Promise-like class with methods to manually resolve or reject, and to attach callbacks.

Custom Promise

A debounce variant that fires the callback on the leading edge (immediately on first call) rather than waiting for the delay to pass.

Debounce with Immediate Flag

Debouncing enhances performance by delaying function execution until a certain period of inactivity, preventing unnecessary calls.

Debounce

Decode an encoded string where patterns like "3[ab]" expand to "ababab", supporting nested patterns.

Decode String

Enhance the Event Emitter class to support method chaining.

Event Emitter II

Emits events and registers listeners for handling asynchronous, event-driven operations.

Event Emitter

Build a fetch wrapper that supports request and response interceptors, similar to how Axios interceptors work.

Fetch Interceptors

Implement a fuzzy search function that finds items where the query characters appear in order, supporting partial and non-consecutive matches.

Fuzzy Search

Convert special characters in a string to their HTML entity equivalents to prevent XSS attacks and ensure safe rendering.

HTML Encode

Build a search engine that indexes documents by their words and supports fast keyword-based search with relevance ranking.

In-Memory Search Engine

Build a simplified version of JSON.parse() that converts a JSON string into a JavaScript value by parsing it character by character.

Implement JSON.parse()

Build your own version of JSON.stringify that serializes JavaScript values to JSON strings.

Implement JSON.stringify()

Implement a Least Recently Used cache with O(1) get and put operations.

LRU Cache

A chaining calculator is a class with methods for arithmetic operations, enabling successive method calls to be linked together in one continuous chain.

Chaining: Calculator

A stack that also tracks minimum and maximum values efficiently, enabling quick retrieval.

Min Max Stack

Implement a priority queue where elements are dequeued based on their priority rather than insertion order.

Priority Queue

Runs a callback when a promise settles, regardless of whether it resolved or rejected, and passes the original value through.

promise.finally( )

Execute async tasks in parallel while tracking priority, resolving with the highest-priority result that succeeds.

Execute Promises with Priority

Converts a callback-based function to a promise-based function.

promisify

Implement the Singleton design pattern to ensure a class has only one instance and provides a global point of access to it.

Singleton Pattern

Build the reactive engine behind a spreadsheet: store formulas, track which cells depend on which, and recompute every dependent in the right order when a cell changes, detecting circular references.

Spreadsheet Engine

Throttling optimizes performance by limiting function execution to a specified rate, preventing excessive calls over short intervals.

Throttle

Implement a Trie (prefix tree) data structure that supports insert, search, startsWith, remove, and find operations for efficient string lookups.