JavaScript Basics

JavaScript Basics

• JavaScript is a high-level, dynamic, and interpreted programming language.
• It's primarily used for client-side scripting on the web, but can also be used for server-side programming, desktop and mobile app development, and game development.
• JavaScript is often used to add interactive elements to websites, create web applications, and manipulate web pages.

Data Types

• Primitive types:
  • Number (e.g., 42)
  • String (e.g., "hello")
  • Boolean (e.g., true or false)
  • Null (e.g., null)
  • Undefined (e.g., undefined)
• Complex types:
  • Object (e.g., {name: "John", age: 30})
  • Array (e.g., [1, 2, 3, 4, 5])

Variables and Operators

• Variables:
  • Declare using let, const, or var
  • Assign values using the assignment operator (=)
• Operators:
  • Arithmetic operators (e.g., +, -, *, /, %)
  • Comparison operators (e.g., ==, !=, ===, !==)
  • Logical operators (e.g., &&, ||, !)
  • Assignment operators (e.g., +=, -=, *=, /=)

Control Structures

• Conditional statements:
  • If statements (e.g., if (x > 5) { ... })
  • If-else statements (e.g., if (x > 5) { ... } else { ... })
  • Switch statements (e.g., switch (x) { case 1: ...; break; case 2: ...; break; ... })
• Loops:
  • For loops (e.g., for (let i = 0; i < 5; i++) { ... })
  • While loops (e.g., while (x > 5) { ... })
  • Do-while loops (e.g., do { ... } while (x > 5))

Functions

• Defining functions:
  • Function declaration (e.g., function add(x, y) { return x + y; })
  • Function expression (e.g., const add = function(x, y) { return x + y; };)
• Function calls:
  • Call a function by using its name followed by parentheses containing arguments (e.g., add(2, 3))

Objects and Arrays

• Objects:
  • Create using object literals (e.g., {name: "John", age: 30})
  • Access properties using dot notation (e.g., obj.name) or bracket notation (e.g., obj["name"])
• Arrays:
  • Create using array literals (e.g., [1, 2, 3, 4, 5])
  • Access elements using index notation (e.g., arr[0])

DOM and Events

• Document Object Model (DOM):
  • A programming interface for HTML and XML documents
  • Allows JavaScript to interact with and manipulate web pages
• Events:
  • Triggered by user interactions (e.g., clicks, hover, scroll)
  • Handled using event listeners (e.g., addEventListener)

JavaScript Basics

• JavaScript is a high-level, dynamic, and interpreted programming language.
• It's primarily used for client-side scripting on the web, but can also be used for server-side programming, desktop and mobile app development, and game development.
• JavaScript is often used to add interactive elements to websites, create web applications, and manipulate web pages.

Data Types

• Primitive types include Number, String, Boolean, Null, and Undefined.
• Complex types include Objects and Arrays.
• Examples of primitive types: Number (e.g., 42), String (e.g., "hello"), Boolean (e.g., true or false), Null (e.g., null), and Undefined (e.g., undefined).
• Examples of complex types: Object (e.g., {name: "John", age: 30}) and Array (e.g., [1, 2, 3, 4, 5]).

Variables and Operators

• Variables are declared using let, const, or var and assigned values using the assignment operator (=).
• Arithmetic operators include +, -, *, /, and %.
• Comparison operators include ==, !=, ===, and !==.
• Logical operators include &&, ||, and !.
• Assignment operators include +=, -=, *=, /=.

Control Structures

• Conditional statements include If, If-else, and Switch statements.
• If statements are used to execute a block of code if a condition is true (e.g., if (x > 5) {...}).
• If-else statements are used to execute a block of code if a condition is true and another block of code if the condition is false (e.g., if (x > 5) {...} else {...}).
• Switch statements are used to execute a block of code based on the value of an expression (e.g., switch (x) { case 1:...; break; case 2:...; break;...}).
• Loops include For, While, and Do-while loops.
• For loops are used to execute a block of code for a specified number of iterations (e.g., for (let i = 0; i < 5; i++) {...}).
• While loops are used to execute a block of code while a condition is true (e.g., while (x > 5) {...}).
• Do-while loops are used to execute a block of code at least once and then continue to execute it while a condition is true (e.g., do {...} while (x > 5)).

Functions

• Functions can be defined using function declarations or function expressions.
• Function declarations are used to define a function (e.g., function add(x, y) { return x + y; }).
• Function expressions are used to define a function and assign it to a variable (e.g., const add = function(x, y) { return x + y; };).
• Functions can be called by using their name followed by parentheses containing arguments (e.g., add(2, 3)).

Objects and Arrays

• Objects are created using object literals (e.g., {name: "John", age: 30}).
• Properties can be accessed using dot notation (e.g., obj.name) or bracket notation (e.g., obj["name"]).
• Arrays are created using array literals (e.g., [1, 2, 3, 4, 5]).
• Elements can be accessed using index notation (e.g., arr[0]).

DOM and Events

• The Document Object Model (DOM) is a programming interface for HTML and XML documents.
• The DOM allows JavaScript to interact with and manipulate web pages.
• Events are triggered by user interactions (e.g., clicks, hover, scroll).
• Events are handled using event listeners (e.g., addEventListener).