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
• What's next

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 scopes and closures
• Arguments & parameters
• Arrow functions

Expressions and operators

Overview: Expressions and operators

• Assignment & Comparisons
• Arithmetic operators
• Bitwise & logical operators
• Conditional (ternary) operator

Numbers and strings

Overview: Numbers and strings

• Numbers
• Number object
• Math object
• Strings
• String object
• Template literals

Representing dates & times

Overview: Representing dates & times

• Date object

Regular expressions

Overview: Regular expressions

• Creating a regular expression
• Writing a regular expression pattern
  • Assertions
  • Character classes
  • Groups and backreferences
  • Quantifiers

Indexed collections

Overview: Indexed collections

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

Typed arrays

Overview: Typed arrays

Iterators and generators

Overview: Iterators and generators

• Iterators
• Iterables
• Generators

Resource management

Overview: JavaScript resource management

• The using and await using declarations
• The DisposableStack and AsyncDisposableStack objects
• Error handling

Internationalization

Overview: Internationalization

• Date and time formatting
• Number formatting
• Collation

JavaScript modules

Overview: JavaScript modules

• Exporting
• Importing
• Default exports and imports
• Avoiding naming conflicts
• Importing JSON modules
• Dynamic module loading
• Top-level await
• Module metadata
• Using modules on the web
• Understanding the module graph
• Modules across platforms

Advanced topics

After you have learned all fundamental features of JavaScript, you can explore some more niche features, or dive deeper into the language's mechanisms and concepts.

• Language overview
• Data structures
• Enumerability and ownership of properties
• Inheritance and the prototype chain
• Equality comparisons and sameness
• Closures
• Meta programming
• Memory management
• Agent communication and coordination

• Next