Lecture 6: JavaScript Functions and Control Structures

1. Introduction to JavaScript

• JavaScript is a high-level, interpreted programming language.
• It plays a vital role in web development by creating interactive user experiences.
• It benefits client-side execution by reducing server load and enhancing interactivity.

2. Variables and Data Types

• Variables act as containers for storing data.
• Declaration Keywords:
  • var: Traditional keyword for variable declaration.
  • let: Allows block-scoped declaration, useful in loops.
  • const: Block-scoped declaration for constants that cannot be reassigned.
• Data Types: Includes numbers, strings, booleans, arrays, and objects.

3. Operators and Expressions

• Arithmetic: $+$, $-$, $*$, $/$, $%$ for mathematical calculations.
• Comparison: $==$, $===$, $!=$, $!==$, $>$, $<$, $>=$, $<=$ for conditions.
• Logical: $&&$ (AND), $||$ (OR), $!$ (NOT) to combine conditions.

4. Functions

• Definition: A block of code designed to perform a specific task.
• Structure: Consists of a function name, parameters (optional), and a function body.
• Return Values: Use the return statement to send a result back to the caller.
• Higher-Order Functions: Functions that take other functions as arguments (like map and reduce) or return them.

5. Control Structures

• Decision-Making:
  • if-else if-else: Executes code based on conditional logic.
  • switch: Simplifies multiple conditions by checking a value against cases.
• Loops (Repetitive Tasks):
  • while: Executes as long as a condition is true.
  • do...while: Executes at least once before checking the condition.
  • for: Controls iterations with initialization, condition, and increment.
• Jump Statements:
  • break: Exits a loop or switch statement prematurely.
  • continue: Skips the current iteration and moves to the next.
  • return: Exits from a function.