Class-3

Class 3 – Introduction to JavaScript

Class Slides: class 3.1

This lecture focuses on arithmetic operations, increment/decrement operators, string concatenation, and user input handling in JavaScript. These fundamental concepts help in performing calculations, manipulating strings, and handling user inputs efficiently.

Key Topics Covered:

1. Arithmetic Operators:

• Enable mathematical calculations such as addition (+), subtraction (-), multiplication (*), division (/), and modulus (%).
• Essential for financial calculations, game mechanics, animations, and data processing.
• Operator precedence follows the BODMAS rule, meaning multiplication and division execute before addition and subtraction.
• Use of parentheses to alter execution order for correct calculations.

2. Increment and Decrement Operators:

• Increment (++) increases a variable’s value by 1.
• Decrement (–) decreases a variable’s value by 1.
• Can be used in two forms:
  • Prefix (++x / –x): The value changes before being used in an expression.
  • Postfix (x++ / x–): The value changes after being used in an expression.
• Frequently used in loops and counters.

3. String Concatenation:

• The + operator joins multiple strings together.
• Numbers and strings can be concatenated to form meaningful messages (e.g., "Score: " + 10).
• Variables can be included in string concatenation to generate dynamic content.

4. User Input Handling:

• Prompt Box (prompt()): Allows users to enter data as a string.
• Parsing Strings to Numbers:
  • parseInt() converts a string into an integer.
  • parseFloat() converts a string into a decimal number.
• Confirm Box (confirm()): Displays a dialog box with “OK” and “Cancel” options, often used for user confirmation.

This session introduces the core mathematical and string operations in JavaScript, providing a foundation for interactive applications. Understanding these concepts is essential for developing dynamic web applications, form validation, and interactive user experiences.