Freea Python course for JavaScript developers

Learn Python through the JavaScript you already know.

Name: Python for JavaScript Developers
Author: Sabry E. Farrag

Side-by-side lessons that map every Python idea to its JS twin, flag the habits that will bite you, and check your code with real Python running in your browser.

lessons: 33; lessons
modules: 13; modules
installs needed: 0; installs needed

const active = users
  .filter((u) => u.active)
  .map((u) => u.name);
console.log(`${active.length} active`);

in Python

.push(x).append(x)=====nullNonearr.lengthlen(arr)`Hi ${name}`f"Hi {name}"else ifelif&& || !and or notcatch (e)except E as ethrowraisethisselfarr.map(fn)[fn(x) for x in arr]Promise.allasyncio.gatherconstructor__init__obj?.a ?? bobj.get("a", b)console.logprintnpm installuv add.push(x).append(x)=====nullNonearr.lengthlen(arr)`Hi ${name}`f"Hi {name}"else ifelif&& || !and or notcatch (e)except E as ethrowraisethisselfarr.map(fn)[fn(x) for x in arr]Promise.allasyncio.gatherconstructor__init__obj?.a ?? bobj.get("a", b)console.logprintnpm installuv add

01/Why

You don't need another beginner course. You need a translation.

Mapped to what you know

Every concept starts from its JavaScript equivalent. Arrays become lists, objects become dicts, Promise.all becomes asyncio.gather.

The traps, called out

Empty arrays that are falsy, mutable default arguments, is versus ==. The habits that quietly break Python code get flagged before they cost you an afternoon.

Real code, really checked

Exercises run on real Python in your browser. Hidden tests check what your code does, so any correct solution passes.

02/How it works

Read it. Write it. Run it.

Every lesson follows the same short loop, so you spend your time on Python, not on figuring out the course.

1Step 1

Read the comparison

The idea in plain words, a quick-reference table and both languages side by side.

.push(x).append(x)

arr.at(-1)arr[-1]

arr.slice(1, 3)arr[1:3]

2Step 2

Write the Python

A focused exercise with an editor that highlights as you type. Hints when you are stuck.

fruits = ["apple", "fig"]
fruits.append("kiwi")
print(fruits[-1])

3Step 3

Get checked for real

Your code runs on Python 3.14 in the browser, with hidden tests for the result.

03/Curriculum

From print() to the tooling real teams ship with.

Foundations

Syntax, data structures and loops: the part you will use every single day.

01
Syntax Bridge
Variables, strings, numbers, conditions
4 lessons
02
Data Structures
Lists, Dicts, Tuples, Sets
3 lessons
03
Loops & Iteration
for, while, for/else, built-ins
- Loops & Control Flow
- Iteration Toolkit
2 lessons

Core Python

Functions, classes, modules, and the gotchas that trip up JavaScript developers.

04
Functions
Args, Comprehensions, Decorators
3 lessons
05
Gotchas & Pitfalls
None, scope, is vs ==
- None, is vs ==
- Scope, Closures & Traps
2 lessons
06
OOP
Classes, Inheritance & Dunder Methods
3 lessons
07
Modules & Errors
import, __main__, try/except
3 lessons

Professional

Files, generators, modern typing, async and testing: what real projects need.

08
File I/O & Data
Files, JSON, regex
- File Operations
- JSON & Regex
2 lessons
09
Generators & Context Managers
yield, lazy evaluation, with
- Generators & Iterators
- Context Managers
2 lessons
10
Modern Python
Dataclasses, types, match/case
3 lessons
11
Async & Testing
asyncio, pytest
- Async/Await
- Testing with pytest
2 lessons

Mastery

The idioms and tooling that make your code look like a Python developer wrote it.

12
Pythonic Patterns
Write like a pro
- Idiomatic Python
- Modern Idioms
2 lessons
13
Ecosystem & Tooling
stdlib, uv, venvs, ruff
- The Standard Library
- Project Setup & Tooling
2 lessons

Notes and quotes

Write notes per lesson, or select any sentence to quote it.

Streaks and goals

A small daily goal and a streak to keep you coming back.

Light and dark

Follows your system theme, switchable any time.

Keyboard friendly

Run and check with shortcuts, accessible to screen readers.

Deep links

Every lesson has its own URL you can bookmark or share.

Open source

MIT licensed. Read the code, suggest a fix, fork it.

04/FAQ

Questions, answered.

Do I need to install Python?

No. Exercises run on real Python (Pyodide, compiled to WebAssembly) inside your browser. The first run downloads the runtime once; after that it is instant.

How are my answers checked?

Two layers. Quick static checks catch JavaScript habits like console.log or ===. Then your code runs together with hidden tests that check what it actually does, so any correct solution passes, not just the reference one.

Who is this for?

Developers who are comfortable with JavaScript or TypeScript and want to become productive in Python quickly. It is not an intro to programming.

Where is my progress saved?

In your own browser. There is no account, no sign-up and no tracking. Clearing your site data resets it.

Which Python version does it teach?

Modern Python: the lessons target 3.12 and newer, and the in-browser runtime is Python 3.14.

Is it free?

Yes. Free and open source under the MIT license.

05/The creator

Designed and built by

Sabry E. Farrag

I built this course for developers who already think in JavaScript and want to be productive in Python, without starting over from “what is a variable”. Every lesson starts from what you know and focuses on what is actually different.

Connect on LinkedIn Star the repo

linkedin.com/in/sabry-elsayed