Functions: Declaration, Expression, and Arrow

// Function declaration — hoisted to the top of its scope
function greet(name) {
  return "Hello, " + name + "!";
}

// Function expression — NOT hoisted
const double = function(n) {
  return n * 2;
};

// Arrow function — concise, no own `this`
const square = (n) => n * n;
const add = (a, b) => a + b;

// Arrow with a block body needs explicit return
const clamp = (n, min, max) => {
  if (n < min) return min;
  if (n > max) return max;
  return n;
};

// Default parameters
function createUser(name, role = "student") {
  return { name, role };
}
createUser("Alice");           // { name: "Alice", role: "student" }
createUser("Bob", "admin");   // { name: "Bob",   role: "admin" }

// Rest parameters — collects remaining args into an array
function sum(...nums) {
  return nums.reduce((acc, n) => acc + n, 0);
}
sum(1, 2, 3, 4); // 10