๐ŸŽ„๐ŸŽ„๐ŸŽ„ New 2024 Year update!

2D graphics and animation with time-travel debugging Leporello.js now supports time-travel debugging for mutable data

Leporello.js

Interactive functional programming IDE for JavaScript

Try online
List of examples showcased in the video

Interactive

Your code is executed instantly as you type, with the results displayed next to it. No need to set breakpoints for debugging. Just move the cursor to any line and see what's happening.

Designed for functional programming

Supercharge your functional code with unprecedented developer tooling.

Next level debugging capabilities

Visualise and navigate a dynamic call graph of your program in a time-travel manner.

Develop HTML5 apps interactively

Modify your code and instantly see the updated version without losing the application state. Interact with your app and debug it later, similar to using a time machine.

Save time when working on IO-heavy programs

IO operations are traced and transparently replayed on subsequent program executions.

Self-hosted

Leporello.js source code is developed within Leporello.js itself

Recent blog entries

  • โ €1 Feb 2024 Teach Programming and Algorithms More Effectively with Leporello.js
  • 20 Jan 2024 Can debugging be liberated from the von Neumann style?
  • โ €8 Jan 2024 Leporello.js now supports time-travel debugging for mutable data

    • Support us

    Leporello.js is funded solely by your donations.

    Support us on GitHub Sponsors and be the first to gain access to the Leporello.js Visual Studio Code plugin with TypeScript support.

    Support