Turtle graphics is a popular way for introducing programming to non-programmers.

This is a simple turtle graphics implementation in JavaScript that works in browser. Imagine a robotic turtle starting at (0, 0) in the x-y plane. Give it the command D(50), and it moves (on-screen) 50 pixels in the direction it is facing, drawing a line as it moves. Give it the command +(45), and it rotates in-place 45 degrees counter-clockwise. There are many other commands as well as variables, conditions, loops and procedures.

Online: https://harag.cz/app/turtle

• 2021-03-02: The first commit
• 2021-04-07: Turtle language finalized (hasn't been touched since)
• 2022-10-12: Examples – from simple to advanced, right next to the editor
• 2022-10-17: Publishing
• 2023-04-08: The codebase moved into this separate Git repository and migrated to Rollup.js
• 2023-04-10: PNG export introduced
• 2023-10-30: Migration to Bootstrap 5

npm install to install dependencies.

npm run build builds the library to dist.

npm run dev builds the library, then keeps rebuilding it whenever the source files change using rollup-watch.

npm test builds the library, then tests it.

• TODO: on exception - ability to determine position in source

Turtle language ideas:

• TODO: (?) allow argument list without parenthesis
• TODO: text - T("hello")
• TODO: stroke pattern - P("dotted"), P("dashed"), P(10, 5)...
• TODO: colors using string - B("red")...
• TODO: bezier curve (B)
• TODO: introduce optimizing painter - merge sequences like DDD, M(10)M(50, 20)...