// 1. Variables and Data Types
const greeting = "Hello, JavaScript world!"; // String (cannot be reassigned)
let counter = 10;                            // Number (can be changed)
const isLearning = true;                     // Boolean

console.log(greeting);

// 2. A Simple Function
// This function takes a name as an input and returns a personalized message
function greetUser(userName) {
    return `Welcome back, ${userName}!`;
}

// Calling the function and saving the result
const userMessage = greetUser("Alex");
console.log(userMessage); 

// 3. Arrays (Lists) and Loops
const programmingLanguages = ["JavaScript", "Python", "C++", "Java"];

console.log("Here are some popular languages:");
// Loop through each item in the array
for (const language of programmingLanguages) {
    console.log(`- ${language}`);
}

// 4. Conditionals (If/Else Statement)
if (counter > 5) {
    console.log("The counter is greater than 5.");
} else {
    console.log("The counter is 5 or less.");
}