Daily JavaScript puzzles
A snippet of JavaScript every day and a poll asking what the console prints. Classes, generators, this, bitwise tricks. Quick, humbling and fun.
What it is
@javascript is an English-language Telegram channel about JavaScript, run by a developer who goes by @nairihar. The bio pitches it as a newsletter with news, articles and books about the language, and adds: don't miss our quizzes. In practice, the quizzes are the main event.
Nearly every day there's a post marked CHALLENGE: a short snippet of code, followed by a poll asking "What is the output?" with a handful of options. Now and then a find slips in between the puzzles. Recently the author wrote up tinyjs, a way to build JavaScript desktop apps under 10MB, and mentioned he'd actually built an app with it.
Why we picked it
The puzzles are tricky without being cruel. Static fields on subclasses, arrow functions and this, getters during destructuring, generators with yield*, a constructor that returns an object, typeof typeof 1, and the classic 1 < 2 < 3 chain. These are exactly the things people trip over in interviews and in real code.
The format is easy to fit into a day. You can answer in under a minute right in the poll and instantly see how everyone else voted. Think of it as a crossword for your morning coffee, if your crossword were written in JavaScript. There's no write-up after the poll, so if you get it wrong you'll have to open a console and work out why, which is honestly where most of the learning happens.
Where to start
- Take the latest puzzle and answer without running the code.
- Then check yourself in the browser console and figure out why it printed what it did.
- Scroll back a bit: the this and class puzzles come almost back to back, a good run for a refresher.
- If a topic stumps you, say yield*, treat it as a nudge to read the docs.
Who it's for
Front-end and Node developers who want to keep their grasp of the language sharp. People prepping for interviews. And learners past the basics, since these puzzles quickly show where your understanding is still shallow.
Quick answers
How often are new puzzles posted? Almost daily: a snippet plus a poll.
Are the answers explained? Not in the channel. You check them yourself in a console.
Who runs it? A developer listed in the bio as @nairihar.
