JavaScript — Part 1

var vs let vs const

Hoisting

Scope Types

Closures 🔥

Primitive Types (7)

💡 Everything else is Object (arrays, functions, dates, regex…)

Type Checking

Falsy & Truthy 🔥

Type Coercion ⚠️

Nullish & Optional Chaining ⭐

Arithmetic & Assignment

Comparison & Logical

Bitwise & Other

if / else / switch

Error Handling

Function Flavors

Arrow vs Regular — key diff

Never use arrow functions as object methods (this will be wrong) or as constructors.

Parameters

Higher-Order Functions ⭐

this keyword

Create & Access

Mutation Methods (change original)

Iteration Methods (return new) 🔥

Non-Mutation Methods

New Array Methods (ES2023+)

Create & Access

Object Methods 🔥

Property Descriptors

Shallow vs Deep Copy

Template Literals

String Methods 🔥

Regex Quick Ref

Loop Types

Iterators & Generators

Array Destructuring

Object Destructuring ⭐

Spread (...)

Rest (...)

💡 Spread expands. Rest collects. Same syntax, opposite job.

var vs let vs const

Hoisting

Scope Types

Closures 🔥

Primitive Types (7)

💡 Everything else is Object (arrays, functions, dates, regex…)

Type Checking

Falsy & Truthy 🔥

Type Coercion ⚠️

Nullish & Optional Chaining ⭐

Arithmetic & Assignment

Comparison & Logical

Bitwise & Other

if / else / switch

Error Handling

Function Flavors

Arrow vs Regular — key diff

Never use arrow functions as object methods (this will be wrong) or as constructors.

Parameters

Higher-Order Functions ⭐

this keyword

Create & Access

Mutation Methods (change original)

Iteration Methods (return new) 🔥

Non-Mutation Methods

New Array Methods (ES2023+)

Create & Access

Object Methods 🔥

Property Descriptors

Shallow vs Deep Copy

Template Literals

String Methods 🔥

Regex Quick Ref

Loop Types

Iterators & Generators

Array Destructuring

Object Destructuring ⭐

Spread (...)

Rest (...)

💡 Spread expands. Rest collects. Same syntax, opposite job.