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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.

Donate to NGO Julenka. Support Ukranians in need. Julenka is an NGO which my brother founded in 2011 to support Ukranian families and kids in need.

Categories 108 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()`

Class

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

Generator

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

Destructuring

array
string
object
defaults
parameters
assign

Promise

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

Reflect

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

Object API

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

Set

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

Map

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

Iterator

array
string
protocol
usage

Object literal

basics
computed properties
getter
setter

Template strings

basics
multiline
tagged template strings
`raw` property

Number API

`Number.isInteger()`
`Number.isNaN()`
`Number.parseInt()`

Symbol

basics
`Symbol.for()`
`Symbol.keyFor()`

Unary Operators

All unary operators
Unary "+" operator
Unary "+" operator, in depth

Spread operator

with arrays
with strings

Rest operator

as parameter
with destructuring

Block scope

`let` declaration
`const` declaration

Arrow functions

basics
function binding

Type conversion

to boolean #planned
to number #planned

Global Object API

`parseInt()`
`parseInt()` in depth #planned

BigInt

Basics

try-catch

unbinded `catch` #planned

Symbol API

`symbol.description` #planned

JSON superset

JSON superset basics #planned

JSON API

well-formed `JSON.stringify()` #planned

Function API

`function.toString()` #planned

Async Function

basics

Modules

`import` statement

Default parameters

Basics

Unicode

in strings