Hoisting

// Function declarations are hoisted ✅
sayHello();  // Works! "Hello, World!"
function sayHello() {
  console.log("Hello, World!");
}

// var is partially hoisted (undefined)
console.log(x);  // undefined (not ReferenceError!)
var x = 10;
console.log(x);  // 10

// What JS actually does with var:
// var x;             ← declaration hoisted
// console.log(x);    ← undefined
// x = 10;            ← assignment stays here
// console.log(x);    ← 10

// let/const — temporal dead zone ❌
// console.log(y);  // ReferenceError: Cannot access 'y' before initialization
let y = 20;
console.log(y);  // 20

// Function expressions are NOT hoisted
// greet();  // ❌ TypeError: greet is not a function
const greet = function() {
  console.log("Hi!");
};
greet();  // ✅ Works after definition

// Best practice: always declare first
const name = "Alice";    // declare at top
const age = 25;
function introduce() {   // declarations can go anywhere (hoisted)
  console.log(`${name}, ${age}`);
}
introduce();