DinoCode
Learn to read code by hunting bugs, then write it yourself.
Reading code is a separate skill from writing it, and almost nobody teaches it on purpose. Every level hands you working-looking code with something wrong in it, and you say which line and why.
Play DinoCodeOpens in a new tab. Playing needs an account, so your progress is kept.
Try it here
This is the opening level. Click the line you believe contains the bug.
Code under review
This function returns the wrong number. One line is responsible.
A playable taste rebuilt here. The full game lives at dinocode.revolucione.se.
What you will work through
- 00Reading a FunctionWhat goes in, what comes back, and how to reach what is inside.
- 01Types & ShapesWhat the compiler actually checks, and what it lets through.
- 02Data MovesReshaping data without wrecking the thing you started with.
- 03Async & the NetworkCode that finishes later, and the lies it tells in the meantime.
- 04React StateWhy the screen didn’t change even though the value did.
- 05EffectsThe single biggest bug farm in real React code.
- 06Components & PropsWhere state should live, and what happens when it lives elsewhere.
- 07The Server BoundaryNext.js: which code runs where, and what must never cross.
- 08The Review BossA real diff. Three bugs. No hints.