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JavaScript - Learn with Katas

Learn and re-learn (all of) JavaScript, at your level and at your speed.

No matter if you are beginner or an expert, a slow or fast learner. The site jskatas aims to allow anyone to discover and learn unknown or new parts of JavaScript. You can also consolidate your JavaScript knowledge or extend your skills and sharpen them.

Learning with jskatas requires you to actively work with and on the language. There is no lean-back content to "just consume" and hope to have acquired knowledge, this is NOT what jskatas offers, and also does not want to offer.

Categories 112 katas

Array API

array.sort() basics
array.sort() can take a compare function
Array.from()
Array.of()
array.fill()
array.find()
array.findIndex()
array.entries()
array.keys()
array.values()
array.includes()
array.flat() #planned
array.flatMap() #planned
stable array.sort() #planned

String API

string.includes()
string.repeat(count)
string.startsWith()
string.endsWith()
string.trimStart()
string.trimEnd() #planned
string.matchAll()
string.matchAll() in depth #planned

Class

creation
accessors
static
extends
more extends
super in method
super in constructor

Destructuring

array
string
object
defaults
parameters
assign

Generator

creation
iterator
yield expressions
send value to a generator
send function to a generator
return inside a generator function

Object API

Object.is()
Object.entries() #planned
Object.values() #planned
Object.fromEntries()
Object.fromEntries() in depth

Map

Basics
map.get()
map.set()
initialize
map.has()

Set

basics
set.add()
set.delete()
the API
set.clear()

Reflect

Basics
Reflect.apply()
Reflect.getPrototypeOf()
Reflect.construct()
Reflect.defineProperty()

Promise

basics
creation
chaining then()
the API
promise.catch()

Template strings

basics
multiline
tagged template strings
raw property

Object literal

basics
computed properties
getter
setter

Iterator

array
string
protocol
usage #planned

Symbol

basics
Symbol.for()
Symbol.keyFor()

Number API

Number.isInteger()
Number.isNaN()
Number.parseInt()
📕 Building the parseInt() Katas

Unary Operators

All unary operators
Unary "+" operator
Unary "+" operator, in depth
📕 What's an "Unary" Operator?

Bitwise Shift Operators

Left Shift "<<" #new
Right Shift ">>" #new
All bitwise shift operators #new

Arrow functions

basics
function binding

Block scope

let declaration
const declaration

Rest operator

as parameter
with destructuring

Spread operator

with arrays
with strings

Global Object API

parseInt()
parseInt() in depth #planned
📕 Building the parseInt() Katas

Type conversion

to boolean #planned
to number #planned

BigInt

Basics

Function API

function.toString() #planned

JSON API

well-formed JSON.stringify() #planned

JSON superset

JSON superset basics #planned

Symbol API

symbol.description #planned

try-catch

unbinded catch #planned

Async Function

basics

Unicode

in strings

Default parameters

Basics

Modules

import statement #planned