Python and JavaScript lessons, from scratch

Your first program, printing to the screen and storing data in variables.

• Hello, world10 exercises
• Variables12 exercises
• Data types11 exercises
• Operations11 exercises
• Asking for input10 exercises
• Project: work out your averageProject · 2 exercises

Make your program decide based on the data.

• Comparisons10 exercises
• if10 exercises
• else and elif10 exercises
• and, or and not10 exercises
• Nested decisions9 exercises
• Project: ticket priceProject · 2 exercises

Repeat without copy and paste: count, add up and search.

• for and range10 exercises
• Accumulators11 exercises
• while9 exercises
• break and continue8 exercises
• Nested loops9 exercises
• Project: FizzBuzzProject · 2 exercises

Give your code a name and use it as often as you like.

• def and return9 exercises
• Parameters10 exercises
• Default values10 exercises
• Scope9 exercises
• Functions that use functions9 exercises
• Project: unit converterProject · 2 exercises

Keep many values together and go through them.

• Creating and indexing10 exercises
• Changing lists11 exercises
• Looping over lists11 exercises
• Slices10 exercises
• Comprehensions12 exercises
• Project: grocery listProject · 3 exercises

Loop over, slice, clean up and format text.

• Indexing text10 exercises
• String methods10 exercises
• f-strings10 exercises
• Looping over text10 exercises
• split and join10 exercises
• Project: password checkerProject · 3 exercises

Store data by name: keys and values.

• Creating and reading10 exercises
• Changing10 exercises
• Looping10 exercises
• Counting with dictionaries10 exercises
• Nested data10 exercises
• Project: contact bookProject · 3 exercises

Data that doesn't change and collections without duplicates.

• Tuples10 exercises
• Unpacking11 exercises
• Sets10 exercises
• Set operations10 exercises
• Choosing the structure10 exercises
• Project: party guest listProject · 3 exercises

Read an error, understand it and keep your program from crashing.

• Reading an error10 exercises
• Common errors10 exercises
• try and except10 exercises
• else and finally10 exercises
• Raising errors10 exercises
• Project: crash-proof calculatorProject · 2 exercises

Flexible functions and functions that take functions.

• *args10 exercises
• **kwargs10 exercises
• lambda10 exercises
• Functions as values10 exercises
• any, all, map and filter10 exercises
• Project: leaderboardProject · 3 exercises

Functions that call themselves.

• What recursion is9 exercises
• Tracing the calls9 exercises
• Recursion with lists9 exercises
• Recursion with text10 exercises
• When not to use it9 exercises
• Project: tower of HanoiProject · 3 exercises

Create your own data types.

• Your first class10 exercises
• __init__ and attributes10 exercises
• Methods11 exercises
• Printing objects10 exercises
• Class attributes10 exercises
• Project: bank accountProject · 3 exercises

Reuse a class to create similar ones.

• Inheriting10 exercises
• super()10 exercises
• Overriding methods9 exercises
• Polymorphism10 exercises
• Composition9 exercises
• Project: game charactersProject · 3 exercises

Less repeated code with Python's built-in tools.

• dataclass10 exercises
• Comparing objects10 exercises
• Properties10 exercises
• Enum10 exercises
• Special methods10 exercises
• Project: shopping cartProject · 3 exercises

Transform data in one line without wasting memory.

• Dictionary and set comprehensions10 exercises
• Comprehensions with conditions10 exercises
• Iterators10 exercises
• Generators with yield10 exercises
• Generator expressions10 exercises
• Project: endless FibonacciProject · 4 exercises

Modules that come with Python.

• import10 exercises
• random with a seed10 exercises
• collections11 exercises
• Dates11 exercises
• JSON10 exercises
• Project: sales reportProject · 3 exercises

Save data and read it back.

• Writing a file10 exercises
• Reading a file10 exercises
• Appending9 exercises
• CSV9 exercises
• JSON in files10 exercises
• Project: expense logProject · 3 exercises

Find and validate patterns in text.

• Finding patterns10 exercises
• Character classes10 exercises
• findall and groups10 exercises
• Replacing10 exercises
• Project: pull out the emailsProject · 3 exercises

Code that other people (and you in a month) can understand.

• Clear names10 exercises
• Small functions10 exercises
• Type hints10 exercises
• Docstrings10 exercises
• Refactoring10 exercises
• Project: clean up this programProject · 3 exercises

Find bugs before someone else does.

• assert9 exercises
• Edge cases9 exercises
• Writing tests9 exercises
• Debugging8 exercises
• Reviewing someone else's code8 exercises
• Project: test a functionProject · 3 exercises

The tools professional libraries use.

• Closures9 exercises
• Decorators8 exercises
• Caching8 exercises
• Context managers9 exercises
• match and case8 exercises
• Project: a call-counting decoratorProject · 3 exercises

What O(1), O(n) and O(n²) mean, and why they matter.

• Counting steps9 exercises
• O(1) and O(n)9 exercises
• O(n²)8 exercises
• O(log n)8 exercises
• Structures and performance8 exercises
• Project: find duplicates fastProject · 3 exercises

The classic algorithms, step by step.

• Linear search9 exercises
• Binary search9 exercises
• Selection sort8 exercises
• Merge sort8 exercises
• Sorting like at work8 exercises
• Project: top threeProject · 3 exercises

Stacks, queues, heaps and graphs.

• Stacks9 exercises
• Queues9 exercises
• Heaps9 exercises
• Graphs9 exercises
• Choosing the structure11 exercises
• Project: the shortest routeProject · 3 exercises

Your first program, printing to the console and storing data in variables.

• Hello, world10 exercises
• Variables11 exercises
• Data types10 exercises
• Operations10 exercises
• Text with variables10 exercises
• Project: work out your averageProject · 5 exercises

Make your program decide based on the data.

• Comparisons10 exercises
• if10 exercises
• else and else if10 exercises
• &&, || and !10 exercises
• The ternary10 exercises
• Project: ticket priceProject · 4 exercises

Repeat without copy and paste: count, add up and search.

• for10 exercises
• Accumulators11 exercises
• while10 exercises
• break and continue9 exercises
• for...of10 exercises
• Project: FizzBuzzProject · 3 exercises

Give your code a name and use it as often as you like.

• function and return9 exercises
• Parameters10 exercises
• Default values10 exercises
• Arrow functions10 exercises
• Scope10 exercises
• Project: unit converterProject · 4 exercises

Keep many values together and go through them.

• Creating and indexing10 exercises
• Changing12 exercises
• Looping10 exercises
• map and filter10 exercises
• reduce and sorting10 exercises
• Project: grocery listProject · 8 exercises

Loop over, slice, clean up and format text.

• Indexing text10 exercises
• String methods10 exercises
• Looping over text10 exercises
• split and join10 exercises
• Formatting10 exercises
• Project: password checkerProject · 8 exercises

Store data by name: properties and values.

• Creating and reading10 exercises
• Changing11 exercises
• Looping10 exercises
• Nested data11 exercises
• Objects and functions10 exercises
• Project: contact bookProject · 4 exercises

Search, sort and copy without breaking what you had.

• Searching11 exercises
• Sorting in depth10 exercises
• Copying and spreading11 exercises
• Set and Map11 exercises
• Choosing the structure10 exercises
• Project: party guest listProject · 4 exercises

Read an error, understand it and keep your program from crashing.

• Reading an error10 exercises
• Common errors10 exercises
• try and catch10 exercises
• finally and throw10 exercises
• Values that aren't there10 exercises
• Project: crash-proof calculatorProject · 3 exercises

Functions that take functions, and functions that remember.

• Functions as values10 exercises
• Rest parameters10 exercises
• Destructuring10 exercises
• Closures9 exercises
• Chaining11 exercises
• Project: leaderboardProject · 3 exercises

Functions that call themselves.

• What recursion is10 exercises
• Tracing the calls10 exercises
• Recursion with arrays10 exercises
• Recursion with text10 exercises
• When not to use it10 exercises
• Project: tower of HanoiProject · 4 exercises

Create your own data types.

• Your first class9 exercises
• constructor and this10 exercises
• Methods10 exercises
• Printing objects10 exercises
• Static methods9 exercises
• Project: bank accountProject · 3 exercises

Reuse a class to create similar ones.

• extends10 exercises
• super()10 exercises
• Overriding methods10 exercises
• Polymorphism10 exercises
• Composition10 exercises
• Project: game charactersProject · 3 exercises

Computed properties, private data and JSON.

• get and set10 exercises
• Private fields10 exercises
• Comparing objects10 exercises
• JSON10 exercises
• Project: shopping cartProject · 3 exercises

Change data without breaking what others are using.

• Copies and references10 exercises
• Methods that change and methods that don't10 exercises
• Updating without mutating10 exercises
• Frozen objects10 exercises
• Project: change historyProject · 3 exercises

Loop your own way and build endless sequences.

• What a for...of can loop over10 exercises
• Generators10 exercises
• Endless sequences10 exercises
• Your own iterable10 exercises
• Project: endless FibonacciProject · 3 exercises

Tools that exist in every JavaScript.

• Math11 exercises
• Numbers10 exercises
• Dates10 exercises
• Regular expressions11 exercises
• Project: pull out the emailsProject · 3 exercises

Code that waits: promises, async and await.

• Why waiting exists9 exercises
• Promises10 exercises
• async and await8 exercises
• Waiting for several things8 exercises
• Project: orders in sequenceProject · 3 exercises

Code that other people (and you in a month) can understand.

• Clear names9 exercises
• Small functions8 exercises
• Commenting what matters8 exercises
• Refactoring9 exercises
• Project: clean up this programProject · 3 exercises

Find bugs before someone else does.

• Checking by hand10 exercises
• Edge cases10 exercises
• Writing tests10 exercises
• Debugging10 exercises
• Reviewing someone else's code10 exercises
• Project: test a functionProject · 3 exercises

What O(1), O(n) and O(n²) mean, and why they matter.

• Counting steps9 exercises
• O(1) and O(n)8 exercises
• O(n²)8 exercises
• O(log n)8 exercises
• Structures and performance8 exercises
• Project: find duplicates fastProject · 4 exercises

The classic algorithms, step by step.

• Linear search10 exercises
• Binary search10 exercises
• Selection sort9 exercises
• Merge sort9 exercises
• Sorting like at work9 exercises
• Project: top threeProject · 3 exercises

Stacks, queues and graphs.

• Stacks10 exercises
• Queues10 exercises
• Linked lists10 exercises
• Graphs10 exercises
• Choosing the structure11 exercises
• Project: the shortest routeProject · 4 exercises