index.md

---

title: JavaScript Guide
slug: Web/JavaScript/Guide
page-type: guide

---

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The JavaScript Guide shows you how to use JavaScript and gives an overview of the language. If you need exhaustive information about a language feature, have a look at the JavaScript reference.

This Guide is divided into the following chapters.

Introduction

Overview: Introduction

• About this guide

• About JavaScript

• JavaScript and Java

• ECMAScript

• Tools

• Hello World

Grammar and types

Overview: Grammar and types

• Basic syntax & comments

• Declarations

• Variable scope

• Variable hoisting

• Data structures and types

• Literals

Control flow and error handling

Overview: Control flow and error handling

• if...else

• switch

• try/catch/throw

• Error objects

Loops and iteration

Overview: Loops and iteration

• for

• while

• do...while

• continue

• break

• for...in

• for...of

Functions

Overview: Functions

• Defining functions

• Calling functions

• Function scope

• Closures

• Arguments & parameters

• Arrow functions

Expressions and operators

Overview: Expressions and operators

• Assignment & Comparisons

• Arithmetic operators

• Bitwise & logical operators

• Conditional (ternary) operator

Numbers and dates

Overview: Numbers and dates

• Number literals

• Number object

• Math object

• Date object

Text formatting

Overview: Text formatting

• String literals

• String object

• Template literals

• Internationalization

• Regular Expressions

Indexed collections

Overview: Indexed collections

• Arrays

• Typed arrays

Keyed collections

Overview: Keyed collections

• Map

• WeakMap

• Set

• WeakSet

Working with objects

Overview: Working with objects

• Objects and properties

• Creating objects

• Defining methods

• Getter and setter

Using classes

Overview: Using classes

• Declaring a class

• Various class features

• Extends and inheritance

• Why classes?

Promises

Overview: Promises

• Guarantees

• Chaining

• Error handling

• Composition

• Timing

Iterators and generators

Overview: Iterators and generators

• Iterators

• Iterables

• Generators

Meta programming

Overview: Meta programming

• Proxy

• Handlers and traps

• Revocable Proxy

• Reflect

JavaScript modules

Overview: JavaScript modules

• Exporting

• Importing

• Default exports

• Renaming features

• Aggregating modules

• Dynamic module loading

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