Functions & Arrow Functions

1// Declaration — hoisted, can call before definition
2function greet(name) {
3  return `Hello, ${name}!`;
4}
5 
6// Expression — NOT hoisted
7const add = function(a, b) {
8  return a + b;
9};
10 
11console.log(greet("Alice")); // Hello, Alice!
12console.log(add(2, 3));       // 5

1// Standard arrow function
2const multiply = (a, b) => {
3  return a * b;
4};
5 
6// Concise body (implicit return)
7const square = (n) => n * n;
8const double = n => n * 2; // Single param: no parens needed
9 
10console.log(multiply(3, 4)); // 12
11console.log(square(5));      // 25
12console.log(double(7));      // 14
13 
14// Arrow in array methods
15const nums = [1, 2, 3, 4, 5];
16const evens = nums.filter(n => n % 2 === 0);
17console.log(evens); // [2, 4]