JavaScript glossary for learners

JavaScript definitions and lessons

1. JavaScript

   JavaScript is the programming language of the web, used for interactive pages, browser APIs, servers, tools, and full-stack applications.

   • what is JavaScript
   • learn JavaScript
   • JavaScript tutorial
   Read the An Introduction to JavaScript lessonExplore An introduction

2. Variable

   A variable is a named storage location for a value. Modern JavaScript code usually declares variables with let or const.

   • JavaScript variables
   • let const JavaScript
   • declare variable JavaScript
   Read the Variables lessonExplore JavaScript Fundamentals

3. Data type

   A data type describes the kind of value JavaScript is working with, such as string, number, boolean, object, null, undefined, symbol, or bigint.

   • JavaScript data types
   • types in JavaScript
   • primitive types JavaScript
   Read the Data types lessonExplore JavaScript Fundamentals

4. Function

   A function is a reusable block of JavaScript behavior that can receive arguments, return a value, and capture surrounding state.

   • JavaScript functions
   • function declaration JavaScript
   • learn JavaScript functions
   Read the Functions lessonExplore JavaScript Fundamentals

5. Arrow function

   An arrow function is a compact function syntax with lexical this behavior, often used for callbacks and short expressions.

   • JavaScript arrow functions
   • arrow function syntax
   • fat arrow JavaScript
   Read the Arrow functions, the basics lessonExplore JavaScript Fundamentals

6. Object

   An object stores keyed values and behavior. Objects are the foundation for many JavaScript patterns, prototypes, and classes.

   • JavaScript objects
   • object properties JavaScript
   • learn JavaScript objects
   Read the Objects lessonExplore Objects: the basics

7. Array

   An array is an ordered list-like object with methods for adding, removing, searching, transforming, and reducing values.

   • JavaScript arrays
   • array methods JavaScript
   • learn JavaScript arrays
   Read the Arrays lessonExplore Data types

8. Map and Set

   Map stores key-value pairs and Set stores unique values. Both are built-in collection types for structured data.

   • JavaScript Map
   • JavaScript Set
   • Map and Set tutorial
   Read the Map and Set lessonExplore Data types

9. Closure

   A closure is a function together with access to the lexical environment where it was created, even after that outer scope has finished running.

   • JavaScript closure
   • what is closure JavaScript
   • lexical environment JavaScript
   Read the Variable scope, closure lessonExplore Advanced working with functions

10. Prototype

    A prototype is the object JavaScript checks when a property is not found directly on an object, enabling prototypal inheritance.

    • JavaScript prototype
    • prototype inheritance
    • prototypal inheritance JavaScript
    Read the Prototypal inheritance lessonExplore Prototypes, inheritance

11. Class

    A class is syntax for creating constructor-based object patterns with methods, inheritance, static members, and private fields.

    • JavaScript classes
    • class syntax JavaScript
    • JavaScript inheritance
    Read the Class basic syntax lessonExplore Classes

12. Module

    A module is a JavaScript file with explicit imports and exports, making code easier to organize and reuse.

    • JavaScript modules
    • import export JavaScript
    • ES modules
    Read the Modules, introduction lessonExplore Modules

13. Promise

    A promise represents an asynchronous result that may fulfill or reject, letting JavaScript code sequence async work clearly.

    • JavaScript promises
    • Promise tutorial
    • asynchronous JavaScript
    Read the Promise lessonExplore Promises, async/await

14. Async/await

    Async/await is syntax for writing promise-based asynchronous JavaScript in a style that reads like sequential code.

    • async await JavaScript
    • learn async await
    • JavaScript async functions
    Read the Async/await lessonExplore Promises, async/await

15. Event loop

    The event loop coordinates JavaScript tasks, rendering, macrotasks, and microtasks so asynchronous work can run on a single thread.

    • JavaScript event loop
    • microtasks macrotasks
    • event loop tutorial
    Read the Event loop: microtasks and macrotasks lessonExplore Miscellaneous

16. DOM

    The Document Object Model is the browser's object representation of a page, allowing JavaScript to read and change elements.

    • JavaScript DOM
    • Document Object Model
    • DOM tutorial
    Read the DOM tree lessonExplore Document

17. Event delegation

    Event delegation handles events on a shared ancestor instead of attaching separate handlers to many child elements.

    • event delegation JavaScript
    • JavaScript browser events
    • DOM events
    Read the Event delegation lessonExplore Introduction to Events

18. Fetch

    Fetch is the browser API for making network requests with promises, commonly used to load JSON and communicate with APIs.

    • JavaScript fetch
    • Fetch API
    • network requests JavaScript
    Read the Fetch lessonExplore Network requests

19. LocalStorage

    LocalStorage is a browser storage API for saving string data across page reloads and browser sessions.

    • localStorage JavaScript
    • browser storage
    • client side storage
    Read the LocalStorage, sessionStorage lessonExplore Storing data in the browser

20. JSON

    JSON is a text format for structured data. JavaScript commonly uses JSON.stringify and JSON.parse to exchange data.

    • JSON JavaScript
    • JSON parse stringify
    • JavaScript JSON tutorial
    Read the JSON methods, toJSON lessonExplore Data types

21. Regular expression

    A regular expression is a pattern for matching text, useful for search, validation, parsing, and string replacement.

    • JavaScript regular expressions
    • RegExp JavaScript
    • regex tutorial
    Read the Patterns and flags lessonExplore Regular expressions

22. Web component

    A web component is a browser-native component model built around custom elements, templates, slots, and shadow DOM.

    • web components JavaScript
    • custom elements
    • shadow DOM
    Read the From the orbital height lessonExplore Web components