Important Concept of JavaScript that SD I/II should know

Difference and Deep Dive intolet, var, const

Closure

Hoisting

Shallow Copy vs Deep Copy

Call, Apply, Bind Methods

Callback Functions, Async Await, Promises

Callback Hell

Promise Methods like.all(), .allSettled(), .any(), .race()

ECMAScript (ES) Features

Prototype and Prototypal Inheritance

Map, Reduce, ForEach, Filter Methods

Currying and it's usage

Arrow Functions

Difference Between Normal and Arrow Functions

Ways to Create Objects

== vs ===

this Keyword in JavaScript

some() Method in JavaScript

Set in JavaScript

Dates in JavaScript

Ways to Call APIs in JavaScript

Object and Array Destructuring

Object Looping Methods

Null Coalescing Operator (??)

Optional Chaining

Pass by Value and Pass by Reference

Scope in JavaScript

Ternary Operator

Type Correction vs Type Coercion

Higher-Order Functions

break, continue Keywords

Function Declaration vs Function Expression

Local Storage and Session Storage

Cookies

JSON Methods

Array Methods

npm vs npx

Handling Missing<!doctype>

pnpm

Draggable Attribute

Null vs Undefined

Skeleton Screen

DRY Principle

ATOMIC Principle

SOLID Principle

Node.js vs JavaScript

Event Propagation

Event Delegation

Template Literals

String Interpolation

Immediately Invoked Function Expressions (IIFE)

Object.freeze()

Object.seal()

Generator Functions

slice() vs splice() Method

Internationalization

Rendering Techniques (CSR, SSR, SSG, ISR)

for vs for..in

Default Parameters

First-Class Functions

Pure vs Impure Functions

String Functions/Operations

String Immutability

DOM (Document Object Model)

Selectors/Query Selector in JavaScript

textContent vs innerHTML

Error Handling in JavaScript

Finally Block

Throwing Errors

Error Propagation and Best Practices

Types of Errors

Set and its Methods

Map vs Object

Event Bubbling

Event Capturing

event.preventDefault()

First-Order Functions

Modules

Post Message for Cross-Origin Communication on Client Side

Promise.all()

Promise.any()

Promise.race()

Strict Mode

eval()

History Access in JavaScript

NaN

isFinite()

Polyfills

Proto vs Prototype

Prototypal Inheritance

isFrozen()

isSealed()

Object.defineProperty()

Execution Context in JavaScript

Macro vs Micro Queue

Design Patterns in JavaScript (Singleton, Abstract, Factory, Builder, Prototypal)

SPA vs MPA

Web Workers and Service Workers

Temporal Dead Zone

Babel

Webpack

HttpRequest

CORS (Cross-Origin Resource Sharing)

Why JavaScript is Single-Threaded?

Ways to Improve Page Performance (Caching Images, CSS Files, etc.)

Prototype Chaining

Mocking Inheritance in JavaScript

Debugging Techniques

Web Accessibility

New HTML5 tags and attributes

Difference between async / Defer on loading scripts

Difference between flex and grid

What are rem and em properties and CSS

Difference way to make webpage responsive

When response sent from server to the browser what gets loaded first ? Html? css? js?

create a css task t make webpage responsive

use of mixins? what are different css libraries you have used?

why functions are called first class citizens in js?

Difference between await and yield keyword?

Sass and CSS libraries

CSS positions

Visibility:hidden vs display:none

Sort an array without using in-build methods of array not event length(hint: use i !== undefined) and using only loop