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// PARAMETERS VS ARGUMENTS

function greet(name) { // 'name' is a parameter

console.log("Hello, " + name);

}

greet("Sarah"); // "Sarah" is an argument

// USING PARAMETERS

function greet(name) {

console.log("Hello, " + name + "!");

}

greet("Alice"); // Hello, Alice!

greet("Bob"); // Hello, Bob!

greet("Charlie"); // Hello, Charlie!

// MULTIPLE PARAMETERS

function calculateArea(width, height) {

const area = width * height;

console.log("The area is: " + area);

}

calculateArea(10, 5); // The area is: 50

calculateArea(7, 3); // The area is: 21

function introduce(name, age, city) {

console.log(name + " is " + age + " years old and lives in " + city);

}

introduce("John", 25, "New York");

// John is 25 years old and lives in New York

// DEFAULT PARAMETERS

greet(); // Hello, undefined

function greet(name = "Guest") {

console.log("Hello, " + name);

}

greet(); // Hello, Guest

greet("Sarah"); // Hello, Sarah

// MORE DEFAULT PARAMETER EXAMPLES

function createUser(username, role = "user", active = true) {

console.log("Username: " + username);

console.log("Role: " + role);

console.log("Active: " + active);

}

createUser("john_doe");

// Username: john_doe

// Role: user

// Active: true

createUser("admin_user", "admin", false);

// Username: admin_user

// Role: admin

// Active: false

// THE ARGUMENTS OBJECT

function showArguments() {

console.log(arguments);

}

showArguments(1, 2, 3, 4, 5);

// [Arguments] { '0': 1, '1': 2, '2': 3, '3': 4, '4': 5 }

// ACCESSING ARGUMENTS OBJECT

function printArguments() {

console.log("First argument: " + arguments[0]);

console.log("Second argument: " + arguments[1]);

console.log("Number of arguments: " + arguments.length);

}

printArguments("Hello", "World", 123);

// First argument: Hello

// Second argument: World

// Number of arguments: 3

// PRACTICAL USE OF ARGUMENTS OBJECT

function sum() {

let total = 0;

for (let i = 0; i < arguments.length; i++) {

total += arguments[i];

}

return total;

}

console.log(sum(1, 2, 3)); // 6

console.log(sum(10, 20, 30, 40)); // 100

console.log(sum(5)); // 5

console.log(sum(1, 2, 3, 4, 5, 6)); // 21

// ANOTHER PRACTICAL EXAMPLE

function findMax() {

let max = arguments[0];

for (let i = 1; i < arguments.length; i++) {

if (arguments[i] > max) {

max = arguments[i];

}

return max;

}

console.log(findMax(5, 12, 3, 9, 1)); // 12

console.log(findMax(100, 50, 200, 75)); // 200

// ARGUMENTS OBJECT LIMITATIONS

function demonstrateArguments() {

// This won't work:

// arguments.forEach(...) // ERROR!

// Convert to real array:

const argsArray = Array.from(arguments);

argsArray.forEach(arg => {

console.log(arg);

});

}

demonstrateArguments("apple", "banana", "cherry");

// apple

// banana

// cherry

// MIXING PARAMETERS AND ARGUMENTS OBJECT

function greetAll(greeting) {

console.log(greeting);

for (let i = 1; i < arguments.length; i++) {

console.log("- " + arguments[i]);

}

greetAll("Welcome:", "Alice", "Bob", "Charlie");

// Welcome:

// - Alice

// - Bob

// - Charlie

// PRACTICAL EXAMPLE

function log(level) {

const timestamp = new Date().toLocaleTimeString();

console.log("[" + timestamp + "] " + level.toUpperCase());

for (let i = 1; i < arguments.length; i++) {

console.log(" " + arguments[i]);

}

log("info", "User logged in", "Session started", "Loading dashboard");

// [2:30:45 PM] INFO

// User logged in

// Session started

// Loading dashboard

log("error", "Connection failed", "Retrying...");

// [2:30:46 PM] ERROR

// Connection failed

// Retrying...