JS Junction

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Basics

Introduction

JavaScript is a scripting language for dynamic web pages, enabling interactivity.

Where To

JavaScript is written inline, in script tags, or external files, with best practices.

Output

JavaScript output uses console.log or innerHTML, avoiding document.write pitfalls.

Syntax

JavaScript syntax uses semicolons and is case-sensitive, with ASI considerations.

Comments

JavaScript comments use // or /* */, supporting JSDoc for documentation.

Variables

JavaScript variables use var, let, or const, preferring let/const for scope.

Scope

JavaScript scope includes global, local, and block, with lexical scope examples.

Hoisting

JavaScript hoisting moves declarations, differing for var vs. let/const.

Errors

JavaScript errors use try-catch, handling SyntaxError and TypeError types.

Data Types

JavaScript data types include strings, numbers, and objects, with null vs. undefined.

Operators

JavaScript operators include arithmetic and logical, with precedence rules.

Ternary Operator

JavaScript ternary operator simplifies conditionals, noting readability concerns.

Short-Circuit Evaluation

JavaScript short-circuit evaluation uses && and || for efficient logic.

If Else

JavaScript if-else statements control flow, referencing ternary operators.

Switch

JavaScript switch statements handle multiple cases, with default case examples.

Loops

JavaScript loops include for, while, and do-while, with break/continue.

For...Of/For...In

JavaScript for...of and for...in iterate iterables and objects, with use cases.

Functions

JavaScript functions use declarations or arrows, noting arrow function gotchas.

this Keyword

JavaScript this keyword varies by context, using bind for control.

Objects

JavaScript objects store properties and methods, supporting class syntax.

Arrays

JavaScript arrays use methods like map and filter for data manipulation.

Strings

JavaScript strings are immutable, with methods like slice and indexOf.

Template Literals

JavaScript template literals enable interpolation, with tagged template support.

Numbers

JavaScript numbers include BigInt, with methods like toFixed for formatting.

Number Properties

JavaScript number properties like MAX_VALUE define numeric limits.

Dates

JavaScript dates use Date objects, handling timezones cautiously.

Math

JavaScript Math object provides methods like random for calculations.

Booleans

JavaScript booleans handle true/false, with truthy/falsy evaluations.

Type Conversion

JavaScript type conversion uses implicit or explicit methods, noting coercion.

Destructuring

JavaScript destructuring extracts array/object values, with rest/spread.

Spread/Rest

JavaScript spread/rest operators handle arrays/objects, distinguishing uses.

RegExp

JavaScript regular expressions use test and exec, with common patterns.

Strict Mode

JavaScript strict mode enforces stricter rules, limiting errors.

Modules

JavaScript ES modules use import/export, supporting dynamic imports.

Security Basics

JavaScript security prevents XSS with safe DOM practices.

Debugging

JavaScript debugging uses console and breakpoints, with debugger statement.

Best Practices

JavaScript best practices include naming and avoiding globals.

Mistakes

JavaScript mistakes include misusing var and ignoring strict mode.

Performance

JavaScript performance optimizes loops and DOM access for efficiency.

Reserved Words

JavaScript reserved words like class restrict variable naming.

Sets

JavaScript Sets store unique values, with methods like add and has.

Maps

JavaScript Maps store key-value pairs, with methods like set and get.

Bitwise

JavaScript bitwise operators like & and | manipulate binary data.

Array Const

JavaScript const arrays prevent reassignment, allowing method mutations.

Object Creation

JavaScript objects are created via constructors or factory functions.

Object Properties

JavaScript object properties use descriptors and Object.defineProperty.

Object Getters/Setters

JavaScript getters and setters manage property access dynamically.

Object Protection

JavaScript object protection uses Object.freeze and Object.seal.

Object Prototypes

JavaScript prototypes enable inheritance for object properties.

Object Display

JavaScript object display uses JSON.stringify for rendering.

Function Parameters

JavaScript function parameters include defaults and rest, with destructuring.

Function Invocation

JavaScript function invocation uses call, apply, and bind for context.

Function Closures

JavaScript closures retain variable scope, with practical examples.

Class Static

JavaScript static methods belong to classes, not instances.

Callbacks

JavaScript callbacks execute functions asynchronously, avoiding callback hell.

Promises

JavaScript Promises handle async operations, with Promise.all for batches.

Async/Await

JavaScript async/await simplifies Promises, handling errors with try-catch.

Fetch API

JavaScript Fetch API retrieves data, with headers and CORS handling.

AJAX

JavaScript AJAX uses XMLHttpRequest for server requests, kept minimal.

Async Patterns

JavaScript async patterns manage parallel or sequential execution.

DOM Methods

JavaScript DOM methods like querySelector access page elements.

DOM Elements

JavaScript DOM elements are created and modified with createElement.

DOM HTML

JavaScript DOM HTML manipulates innerHTML, with XSS precautions.

DOM Forms

JavaScript DOM forms use FormData for validation and submission.

DOM CSS

JavaScript DOM CSS modifies styles via style and classList properties.

DOM Events

JavaScript DOM events use addEventListener for interactivity.

DOM Navigation

JavaScript DOM navigation uses parentNode and querySelectorAll.

DOM Nodes

JavaScript DOM nodes include types and collections for manipulation.

DOM Accessibility

JavaScript DOM accessibility uses ARIA and keyboard events.

DOM MutationObserver

JavaScript MutationObserver tracks DOM changes, enabling reactivity.

Window

JavaScript window object provides browser properties and methods.

Screen

JavaScript screen object provides dimensions and orientation data.

Location

JavaScript location object manipulates URLs, with search parsing.

History

JavaScript history API uses pushState for navigation, with popstate.

Navigator

JavaScript navigator object provides browser info, noting userAgent limits.

Timing

JavaScript timing uses setTimeout and setInterval for scheduling.

Cookies

JavaScript cookies store data, with SameSite for security.

Clipboard API

JavaScript Clipboard API reads/writes clipboard, with permissions.

Popup Alert

JavaScript popup alerts use alert, confirm, and prompt for user input.

Web Storage API

JavaScript Web Storage API uses localStorage, with size limits.

Web Geolocation API

JavaScript Geolocation API retrieves locations, with error handling.

Web Worker API

JavaScript Web Worker API runs background scripts, with termination.

Web History API

JavaScript Web History API supports SPA navigation with pushState.

Web Validation API

JavaScript Web Validation API uses checkValidity for form checks.

Web Speech API

JavaScript Web Speech API enables speech synthesis and recognition.

Web IntersectionObserver

JavaScript IntersectionObserver tracks element visibility for lazy loading.

Web ResizeObserver

JavaScript ResizeObserver monitors element size changes dynamically.

JSON Syntax

JavaScript JSON syntax structures data, validated with JSONLint.

JSON Data Types

JavaScript JSON data types exclude undefined, supporting objects.

JSON Parse

JavaScript JSON.parse converts strings to objects, with error handling.

JSON Stringify

JavaScript JSON.stringify converts objects to strings, with replacers.

JSON Objects

JavaScript JSON objects use dot notation for nested data access.

JSON Arrays

JavaScript JSON arrays support iteration for data processing.

JSON Security

JavaScript JSON security avoids eval, using JSON.parse for safety.

Event Delegation

JavaScript event delegation uses bubbling for efficient event handling.

Debouncing

JavaScript debouncing optimizes performance, used in search inputs.

Throttling

JavaScript throttling limits execution, used in scroll events.

Form Validation

JavaScript form validation uses Validation API for user input checks.

Dynamic Lists

JavaScript dynamic lists create and update DOM elements with appendChild.

AJAX Fetch

JavaScript AJAX Fetch retrieves and displays data, with error handling.

LocalStorage CRUD

JavaScript localStorage CRUD manages data with JSON serialization.

Simple Animation

JavaScript animations use requestAnimationFrame, with CSS fallbacks.

Search Filter

JavaScript search filter uses Array.filter for dynamic list filtering.

Toggle Visibility

JavaScript toggle visibility uses aria-hidden for accessibility.

JS Junction

Basics

Objects

Functions

Async

HTML DOM

Browser BOM

Web APIs

JSON

Patterns

Examples