History
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- How :
- Developed by Brendan Eich in 1995 at Netscape.
- Initially created in just 10 days as a client-side scripting language for web browsers.
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- Who :
- Brendan Eich, co-founder of Mozilla and creator of JavaScript.
- Netscape Communications Corporation.
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- Why :
- To enable dynamic and interactive web content.
- To complement HTML and CSS for enhanced web development.
Introduction
Advantages :
Asynchronous Programming (Promises, Async/Await).
JavaScript Design Patterns (Module, Singleton, Observer).
Prototypal Inheritance and ES6 Classes.
TypeScript and Typed JavaScript.
Disadvantages :
Browser inconsistencies in older versions.
Lack of strong typing can lead to runtime errors.
Complexities in large-scale application development.
Notes
You can Direcly create page by write {filename}.js
console.log("msg") - Print that msgconsole.warn('hello %s', 'Cheekbone') - The %s is a placeholder for a string, allowing you to format the message with additional variables.console.error(new Error(‘Oops!‘)) - console.error(new Error(‘Oops!’));
In Html use <script {You can Give link path or ⇒ } > write Here this tag for write js
variables Types
Primitive Types :
String : Represents text (e.g., "Hello, world!").Number : Represents numeric values (e.g., 42, 3.14).BigInt : Represents integers of arbitrary precision (e.g., 12345678901245678901234567890n).Boolean : Represents a logical entity that can be either true or false.Undefined : A variable that has been declared but has not been assigned a value(e.g., let a;).Null : Represents the intentional absence of any value (e.g., let b = null;).Symbol : A unique and immutable primitive value often used as object property keys.
Object Types :
Object : A collection of key-value pairs (e.g., { name: "Alice", age: 25 }).Array : A special type of object for storing ordered lists (e.g., [1, 2, 3]).Function : A callable object that can be defined with the function keyword (e.g., function add(a, b) { return a + b; }).Date : A built-in object for working with dates and times (e.g., new Date()).RegExp : Regular expressions for pattern matching in strings (e.g., /abc/).
Scope Types
Global Scope : Variables declared outside any function or block. Accessible anywhere in the code.
Function Scope : Variables declared inside a function using var. Accessible only within that function.
Block Scope : Variables declared with let or const within a block (e.g., inside {} braces). Accessible only within that block.
let vs var
Loops with closures
Operators
Arithmetic Operators
+ (Addition)- (Subtraction)* (Multiplication)/ (Division)% (Modulus)** (Exponentiation)
Assignment Operators
= (Assign)+= (Add and assign)-= (Subtract and assign)*= (Multiply and assign)/= (Divide and assign)%= (Modulus and assign)**= (Exponentiation and assign)
Comparison Operators
== (Equal to)=== (Strict equal to)!= (Not equal to)!== (Strict not equal to)> (Greater than)< (Less than)>= (Greater than or equal to)<= (Less than or equal to)
Logical Operators
&& (Logical AND)|| (Logical OR)! (Logical NOT)
Bitwise Operators
& (Bitwise AND)| (Bitwise OR)^ (Bitwise XOR)~ (Bitwise NOT)<< (Left shift)>> (Right shift)>>> (Unsigned right shift)
Unary Operators
++ (Increment)-- (Decrement)+ (Unary plus)- (Unary negation)typeof (Returns the type of a variable)void (Evaluates an expression and returns undefined)delete (Deletes a property from an object)
Ternary Operator
A shorthand for if...else statements.
condition ? exprIfTrue : exprIfFalse
Comma Operator
Allows multiple expressions to be evaluated, returning the value of the last expression.
expr1, expr2, expr3
Spread and Rest Operators
Spread Operator : ... (expands an iterable into individual elements)Example: let arr = [1, 2]; let newArr = [...arr, 3];
Rest Operator : ... (gathers multiple elements into an array)Example: function myFunc(...args) { /* args is an array */ }
Instanceof Operator
Tests whether an object is an instance of a specific constructor.
object instanceof Constructor
In Operator
Checks if a property exists in an object.
property in object
JavaScript Conditionals
if Statement
Ternary Operator
else if
switch Statement
vs =
JavaScript Functions
Functions
Anonymous Functions
return Keyword
Calling Functions
Function Expressions
Function Parameters
Function Declaration
Arrow Functions (ES6)
JavaScript Arrays
Mutable chart
Arrays
Property .length
Index
Method .push()
Method .pop()
Method .shift()
Method .unshift()
Method .concat()
More Methods
JavaScript Loops
While Loop
Reverse Loop
Do…While Statement
For Loop
Looping Through Arrays
Break
Continue
Nested
for…in loop
for…of loop
JavaScript Iterators
Functions Assigned to Variables
Callback Functions
Array Method .reduce()
Array Method .map()
Array Method .forEach()
Array Method .filter()
JavaScript Objects
Accessing Properties
Naming Properties
Non-existent properties
Mutable
Assignment shorthand syntax
Delete operator
Objects as arguments
Shorthand object creation
this Keyword
Factory functions
Methods
Getters and setters
JavaScript Classes
Static Methods
Class
Class Constructor
Class Methods
extends
JavaScript Modules
Export
Import
Export Module
Require Module
JavaScript Promises
Promise states
Executor function
setTimeout()
.then() method
.catch() method
Promise.all()
Avoiding nested Promise and .then()
Creating
Chaining multiple .then()
Fake http Request with Promise
JavaScript Async-Await
Asynchronous
Resolving Promises
Async Await Promises
Error Handling
Aysnc await operator
JavaScript Requests
JSON
XMLHttpRequest
GET
POST
fetch api
promise url parameter fetch api
Fetch API Function
async await syntax
Library & Frameworks
React js - This is Use Full for Front-end single page web applicationNode Js - JavaScript runtime built on Chrome’s V8 engine for building fast and scalable server-side applications.jQuery - Simplifies DOM manipulation.Lodash - Utility library for JavaScript.Angular - Platform for building mobile and desktop web applications.Vue.js - Progressive framework for building user interfaces.
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