Top all-time · #4272
RunJS
Company blog · runjs.app/blogprogramming
RunJS is the company blog at runjs.app, writing about programming. Since 2021, 18 different Hacker News readers have linked it 23 times, most often “RunJS – A Playground for JavaScript and TypeScript”. It is still writing: the last post was on 2026-08-17, and you can follow it by feed.
Too few sampled comments (10) to say how often HN recommends it.?
Why HN links it
HN commenters mention RunJS mostly as a browser-based JavaScript scratchpad and playground for trying out code. None of the comments discuss the blog's writing; one links a blog post on equations as a JavaScript example.
Summarised by Claude from a sample of 10 HN comments that link here. Each comment is marked recommending, critical or neutral (citing without judging); how this works.
Live results as you type. Built-in Node.js and browser environments, install npm packages, prototype UI live - no project, no setup, no signup. Mac, Windows, Linux.
Most-linked posts?
- RunJS – A Playground for JavaScript and TypeScript7 people · 7 mentions · first linked 2021-02-03
- Equations That Changed the World – Rewritten in JavaScript6 people · 6 mentions · first linked 2024-02-20
- Music Theory for Programmers3 people · 4 mentions · first linked 2026-08-18
- /2 people · 2 mentions · first linked 2022-04-22
What Hacker News says?
have you tried RunJS? https://runjs.app/
Comment linking /
on “Show HN: Heynote – A dedicated scratchpad for developers”Submitted Music Theory for Programmers as a story · 404 points
HN discussionI built https://runjs.app because I wanted an easy way to run JavaScript and test out ideas. It turned out that a lot of other people wanted the same thing. The first version was free and very basic. After getting a lot of suggestions and feedback from the people using it, I added more features and introduced a freemium pricing model.
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on “Ask HN: Those making $500/month on side projects in 2024 – Show and tell”Submitted Music Theory for Programmers as a story · 6 points
HN discussionI still enjoyed going through it, for what it is. 1. runjs promoting itself using music REPL as an example 2. author used LLM to fit a few music related ideas into the web audio API 3. they tried it with math two years ago: https://runjs.app/blog/equations-that-changed-the-world-rewr... They are clearly targeting js developers, which is one of the largest coding community 4. "The naming is not arbitrary, and the har…
Comment linking /blog/equations-that-changed-the-world-rewritten-in-javascript
on “Music Theory for Programmers”Submitted Music Theory for Programmers as a story · 4 points
HN discussionLast week I tried to buy RunJS ( http://runjs.app ), which uses Paddle. It wouldn't take my business credit card, so I emailed the creator. He said it's a Paddle problem and gave me Paddle's email. I sent Paddle an email explaining what I was trying to buy, with a screenshot of the payment modal and error message, and their reply was an email bot that said: > I wasn't able to tell exactly which transaction you're re…
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on “Help HN: Stripe shutting us down with 48 hours notice on a holiday skeleton crew”Submitted Show HN: A JavaScript playground that shows the result of each expression as a story · 3 points
HN discussionMe too - I currently use https://runjs.app/ while developing but this would fit better.
Comment linking /
on “Show HN: Edna, note taking app for developers”Submitted Equations That Changed the World – Rewritten in JavaScript as a story · 3 points
HN discussionTo try out simple things I like to use https://runjs.app/
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on “Node.js Notebooks”Submitted Equations That Changed the World – Rewritten in JavaScript as a story · 2 points
HN discussionhttps://runjs.app/ is also another player in this area, though is its own editor.
Comment linking /
on “Show HN: Sunflower Editor – like adding console.log to every line of your code”Submitted Equations That Changed the World – Rewritten in JavaScript as a story · 2 points
HN discussionGreat advice, that's why I bought https://runjs.app/ (not affiliated), I can quickly prototype pretty much anything with this and then port it to my actual target lang/framework after. Not hampered by the browser, npm, project setup or privacy concerns.
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on “Ask HN: What are the best programming tricks you know?”Submitted Equations That Changed the World – Rewritten in JavaScript as a story · 2 points
HN discussionI use the browser's dev console to try out short JS snippets or for simple on-page scraping. (for longer JS as a scratchpad I use https://runjs.app ). The browser's dev console gives you access to the current page's DOM, plus anything you can do in JS. So stuff like `document.querySelectorAll(".foo")` works. Also `fetch()` works within the page's context. Apart from that, what are some other useful things one can do…
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on “The Front-End Developer's Guide to the Terminal”Submitted Mathematical Notation for JavaScript Developers Explained as a story · 2 points
HN discussionAt least in V8, this is not the case. To prove it, start a Chromium-based browser with the command-line flag --js-flags=--expose-gc, then go to https://runjs.app/play/#aWYgKCF3aW5kb3cuZ2MpIHsKICB0aHJvdyBu...
Comment linking /play/
on “A job queue in two lines of JavaScript”Submitted Music Theory for Programmers as a story · 1 points
HN discussionSubmitted Equations that changed the world – rewritten in JavaScript as a story · 1 points
HN discussionSubmitted RunJS – A Playground for JavaScript and TypeScript as a story · 1 points
HN discussionSubmitted RunJS – A Playground for JavaScript and TypeScript as a story · 1 points
HN discussion
