// Use const for values that do not change
const name = "TechYouHigh";

// Use let for values that can change
let age = 25;
age = 26; // OK

// Avoid var (old syntax)
var oldVariable = "to avoid";

// String
const text = "Hello";

// Number
const number = 42;
const decimal = 3.14;

// Boolean
const isTrue = true;
const isFalse = false;

// Null and Undefined
const empty = null;
let notDefined;

// Array
const fruits = ["apple", "banana", "orange"];

// Object
const person = {
  name: "John",
  age: 30,
  city: "Paris",
};

// Classic function
function greet(name) {
  return `Hello ${name}!`;
}

// Arrow function
const greetArrow = (name) => {
  return `Hello ${name}!`;
};

// Short arrow function
const greetShort = (name) => `Hello ${name}!`;

console.log(greet("Mary")); // "Hello Mary!"

const numbers = [1, 2, 3, 4, 5];

// map: transform each element
const doubles = numbers.map((n) => n * 2);
// [2, 4, 6, 8, 10]

// filter: filter elements
const evens = numbers.filter((n) => n % 2 === 0);
// [2, 4]

// reduce: reduce to a single value
const sum = numbers.reduce((acc, n) => acc + n, 0);
// 15

// find: find an element
const found = numbers.find((n) => n > 3);
// 4

// Promise
function fetchData() {
  return new Promise((resolve) => {
    setTimeout(() => {
      resolve("Data loaded");
    }, 1000);
  });
}

// Async/Await
async function loadData() {
  try {
    const data = await fetchData();
    console.log(data);
  } catch (error) {
    console.error("Error:", error);
  }
}

loadData();

// Destructuring (standalone example)
const person2 = { name: "John", age: 30, city: "Paris" };
const fruits2 = ["apple", "banana", "orange"];

const { name: name2, age: age2 } = person2;
const [first, second] = fruits2;

// Template literals
const message = `${name2} is ${age2} years old`;

// Spread operator
const newArray = [...fruits2, "kiwi"];
const newObject = { ...person2, city: "Lyon" };