Hands-on JavaScript tutorials that explain how code works, not just what to type. Each one walks through a concept or a classic interview problem step by step, with runnable code. If you’re new, work through the sections in order: fundamentals first, then data structures, then algorithm problems.
1. Fundamentals: start here
The core JavaScript concepts everything else builds on: variables and scope, recursion, array methods, memoization, and programming styles.
See all fundamentals tutorials →
2. Data structures
Build the structures interviewers ask about from scratch: linked lists, stacks, queues, hash tables, and binary search trees. Building them yourself is the fastest way to understand when to use each one.
See all data structures tutorials →
3. Algorithm design breakdowns
Classic coding-interview problems solved step by step, from Two Sum to Number of Islands. Each breakdown covers the brute-force approach, the optimal solution, and its time and space complexity.
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Solving the “Longest Increasing Subsequence” Problem in JavaScript
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Solving the “Number of Islands” Problem in JavaScript
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Solving the “Two Sum” Problem in JavaScript
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Sorting Characters by Frequency in JavaScript
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Solving the “Palindrome Permutation” Problem in JavaScript
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Solving the “Rotate a Matrix” Problem in JavaScript
See all algorithm breakdowns →
4. Advanced topics
Deeper, real-world engineering topics, such as authenticating with OAuth 2.0.
Preparing for a career change? Our Learn to Code guides cover the tools and paths that come before interview prep.