Class-2

Class 2 –  Introduction to JavaScript

Class Slides: class 2.1

This lecture covers the fundamentals of variables, data types, statements, expressions, and operators in JavaScript. These concepts form the foundation for writing efficient and structured JavaScript code.

Key Topics Covered:

1. Variables and Memory Storage:

• Variables store values in memory, allowing easy retrieval and manipulation.
• Declaring variables using var, let, and const:
  • var (deprecated for modern use).
  • let (preferred for reassignable variables).
  • const (for constants that don’t change).
• JavaScript assigns undefined as the default value for uninitialized variables.

2. JavaScript Data Types:

• Primitive Data Types:
  • Number (e.g., 10, 3.14).
  • String (e.g., "Hello", 'World').
  • Boolean (true/false values).
  • Null (intentional empty value).
  • Undefined (declared but not assigned a value).
  • Symbol (unique values used in advanced programming).
• Non-Primitive (Complex) Data Types:
  • Objects (store key-value pairs).
  • Functions (callable blocks of code).
  • Arrays (ordered lists of values).

3. JavaScript Statements and Expressions:

• Statements: Instructions executed in order (e.g., let a = 5;).
• Expressions: Combinations of values, variables, and operators that return a result (e.g., a + b).
• Comments:
  • Single-line (// This is a comment).
  • Multi-line (/* This is a multi-line comment */).

4. Rules for Variable Naming:

• Cannot contain spaces.
• Can include letters, numbers, underscores (_), and dollar signs ($).
• Cannot start with a number.
• Case-sensitive (e.g., num and Num are different).
• Camel case (myVariableName) is recommended for readability.

5. JavaScript Operators:

• Arithmetic Operators: Perform basic math operations (+, -, *, /, %, **).
• Assignment Operators: Assign values (=, +=, -=, *=, /=).
• BODMAS Rule: Ensures correct execution order in arithmetic operations.

The lecture established a strong understanding of variables, data types, statements, and operators in JavaScript. These are essential for writing dynamic and interactive programs in web development.