Introduction to JavaScript

JavaScript is a versatile, high-level programming language and one of the core technologies of the World Wide Web, alongside HTML and CSS.

JavaScript is a single-threaded language, meaning it executes one task at a time by default. However, through mechanisms like the Event Loop, callbacks, and asynchronous programming (such as Promises and Async/Await), it can efficiently handle multiple operations—like fetching data from servers—without blocking the user interface.

Table of Contents

• 01 Data Types
  • 01.1 Primitive Data Types
    • 01.1.1 Number
    • 01.1.2 BigInt
    • 01.1.3 String
      • 01.1.3.1 String literals
      • 01.1.3.2 Find Length of a String
      • 01.1.3.3 Bracket Notation in Strings
      • 01.1.3.4 Concatenate Strings
      • 01.1.3.5 Escape Sequence in Strings
    • 01.1.4 Boolean
    • 01.1.5 Null
    • 01.1.6 Undefined
    • 01.1.7 Symbol
  • 01.2 Non-Primitive Data Types
    • 01.2.1 Object
    • 01.2.2 Array
    • 01.2.3 Function
      • 01.2.3.1 Passing values to a Function with Arguments
      • 01.2.3.2 Function with Return Value
    • 01.2.4 Date
    • 01.2.5 RegExp
• 02 Variables
  • 02.1 var
  • 02.2 let
  • 02.3 const
• 03 Hoisting
  • 03.1 Variable Hoisting
    • 03.1.1 var Hoisting
    • 03.1.2 let and const Hoisting
  • 03.2 Function Hoisting
    • 03.2.1 Function Declaration
    • 03.2.2 Function Expression
• 04 Scopes
  • 04.1 Global Scope
  • 04.2 Function Scope
  • 04.3 Block Scope
  • 04.4 Lexical Scope
• 05 Operators
  • 05.1 Arithmetic Operators
  • 05.2 Assignment Operator
  • 05.3 Compound Assignment
  • 05.4 typeof Operator
• 06 Type Coercion
  • 06.1 Implicit Coercion
    • 06.1.1 String Coercion
    • 06.1.2 Numeric Coercion
    • 06.1.3 Boolean Coercion
  • 06.2 Explicit Coercion
    • 06.2.1 Explicit Conversion to Number
    • 06.2.2 Explicit Conversion to String
    • 06.2.3 Explicit Conversion to Boolean
• 07 Equality
  • 07.1 Loose Equality ==
  • 07.2 Strict Equality ===
• 08 Falsy and Truthy
  • 08.1 Falsy values
  • 08.2 Truthy values
• 09 Conditions
  • 09.1 If
    • 09.1.1 If Else
    • 09.1.2 Nested If Else
  • 09.2 Ternary Operator
    • 09.2.1 Nested Ternary
  • 09.3 Switch