for...of & for...in Loops

// for...of — iterate VALUES (arrays, strings)
const colors = ["red", "green", "blue"];
for (const color of colors) {
  console.log(color);  // "red", "green", "blue"
}

// for...of with strings
for (const char of "Hello") {
  console.log(char);  // "H", "e", "l", "l", "o"
}

// for...in — iterate KEYS (objects)
const user = { name: "Alice", age: 25, role: "Admin" };
for (const key in user) {
  console.log(`${key}: ${user[key]}`);
}
// name: Alice, age: 25, role: Admin

// ❌ DON'T use for...in on arrays
const nums = [10, 20, 30];
for (const i in nums) {
  console.log(typeof i);  // "string" — i is "0", "1", "2" not 0, 1, 2
}

// ✅ Use for...of for arrays
for (const num of nums) {
  console.log(num);  // 10, 20, 30 (actual values)
}