fibonacci.js

123456

function fib(n) { if (n <= 1) return n; return fib(n - 1) + fib(n - 2); } // Watch the cats react to a clean run console.log(fib(10));

🐈

JS

The Fibonacci Bounce

Clean output triggers the parade. All the cats march left to right — every single time code runs without errors.

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hello.js

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// Your very first run in the editor. // The cats have been waiting. console.log("Hello, world!"); console.log("The cats are awake."); console.log("All of them.");

🎉

JS

Hello World Party

Your first run in a fresh session triggers the milestone cat — confetti, a tiny hat, full celebration mode.

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oops.js

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const user = { name: "Ada" }; // This will throw a TypeError user.greet(); // Fix the error to calm the hisser console.log("Never reached");

😾

JS

Error Head-Tilt

A runtime error makes the hisser arch its back. Fix the bug and the cat immediately settles — it's watching you.

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todo.js

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// TODO: implement this properly // TODO: also this // TODO: and definitely this function doTheThing() { return null; // placeholder }

😴

JS

TODO Nap Corner

Three or more TODO comments summons the nap cat. It curls up on your unfinished work and breathes softly. Not helpful. Very cozy.

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summon.js

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// Type this magic word and run it. // Seven hand-crafted designs. // One will appear in the output. const spell = ":cat"; console.log(spell); // Watch the console. 🐱

🔮

JS

The ASCII Summoning

Log :cat to the console and a hand-drawn ASCII cat appears in amber. Seven designs, randomly selected. Try a few.

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keeprunning.js

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// Keep hitting Ctrl+Enter. // The cats track every run. // 1st, 10th, 25th, 50th runs // each trigger a full party. 🎊 const msg = "run #" + Date.now(); console.log(msg);

🏆

JS

50-Run Milestone

The milestone cat remembers every run across sessions. Hit 1, 10, 25, or 50 runs and it throws a full party. It has a hat. Earned.

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loop.py

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# A loop that produces no output. # The cats get suspicious. total = 0 for i in range(100): total += i # Empty output, still a clean run

🤨

Python

The Silent Loop

Code that runs clean but produces no output still triggers the parade — the cats celebrate correctness, not noise.

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colony.py

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cats = { "hisser": "errors", "napper": "todos", "parader": "clean runs", } print(cats)

😸

Python

Python Dictionary Dance

A minimal Python script that prints the colony roster. Runs clean, triggers the parade, and makes a surprisingly good wallpaper.

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