Developers - from junior to senior
Sharpen your JavaScript, learn the less obvious behaviours of the language and hone your craft on real examples - from the basics to advanced quirks.
SolveJS - practice JavaScript through puzzles
Learn the real quirks of JavaScript and the browser dev tools by solving puzzles. For developers, testers and coding enthusiasts. The core is free - you do not pay with your data.
The whole core is free. You only create an account for the leaderboard and points.
The site already has 211 puzzles – all free. You can solve 7 right away in the demo, no login.
Who SolveJS is for
Testers and QA
Practice reading code, predicting application behaviour and working with browser dev tools (DevTools) - skills useful in day-to-day testing of web apps.
Enthusiasts and learners
Love puzzles and want to learn to code in JavaScript? Start with Warm-up and climb the leaderboard while learning through play.
Why do it and what you gain
You learn by solving
Instead of passive reading, you write code, predict output and dig through DevTools. Knowledge sticks because you earn it in practice.
You meet the real JavaScript quirks
Hoisting, == comparisons, type coercion, event loop ordering, closures - the moments every JavaScript developer trips on.
You practice the browser dev tools
The DevTools family teaches the Elements, Network, Application and Console panels plus tampering with GET and POST requests - which Codewars and JSchallenger do not have.
You track progress and compete
Every solved puzzle earns points and moves you up the weekly and global leaderboard. The account is free and only serves competition.
Several ways to play
SolveJS has several ways to play - twelve challenge types across three categories. Each trains a different skill.
Coding
Write functions, fix bugs, unlock a goal. Code runs in an isolated Web Worker.
Analysis
Predict console output and decode strings. The JS quirks everyone trips on.
DevTools
Find the flag in DevTools and tamper GET/POST requests. Codewars and JSchallenger do not have this.
See the detailed description of all 12 types on the demo page →
How it works
- Pick a puzzle from the list - by level, category and type.
- Solve it in the browser. Code runs in an isolated Web Worker - you install nothing.
- Earn points and jump into the weekly and global leaderboard.
Five difficulty levels
From Warm-up, through Easy, Medium and Hard, up to Expert. You start gently and raise the bar step by step.
Warm-upEasyMediumHardExpert
You do not pay with your data
We never sell your data and never send ads. We count stats in-house, with no external trackers. The core is and will stay free.
Start now - for free
Create a free account and unlock the full set of puzzles, points and the leaderboard. Or check the demo first, no login required.