Convert the following function to an arrow function:

1. Function: `function add(a, b) { return a + b; }`
2. Write it as `const add = ...`
3. Shorten it to a single-line implicit return.

const add = (a, b) => a + b;

You have an array `[1, 2, 3]`:

1. Use `map` to create a new array of squares (each number times itself).
2. Expected result: `[1, 4, 9]`.

const numbers = [1, 2, 3];
const squared = numbers.map(num => num * num);

console.log(squared);

You have an ages array `[15, 22, 18, 10, 30]`:

1. Use `filter` to create a new array with adults only (>= 18).

const ages = [15, 22, 18, 10, 30];
const adults = ages.filter(age => age >= 18);

console.log(adults); // [22, 18, 30]

You have `user = { name: "Ali", email: "ali@test.com" }`:

1. Extract `name` and `email` into separate variables.
2. Log the new variables.

const user = { name: "Ali", email: "ali@test.com" };
const { name, email } = user;

console.log(name, email);

Merge two arrays:

1. First array `arr1 = [1, 2]`.
2. Second array `arr2 = [3, 4]`.
3. Create `arr3` combining both using `...` (spread).

const arr1 = [1, 2];
const arr2 = [3, 4];
const arr3 = [...arr1, ...arr2];

console.log(arr3); // [1, 2, 3, 4]

Find an item in an array of objects:

1. You have `users = [{id: 1, name: "A"}, {id: 2, name: "B"}]`.
2. Use `find` to get the user with `id` 2.

const users = [{id: 1, name: "A"}, {id: 2, name: "B"}];
const user = users.find(u => u.id === 2);

console.log(user); // {id: 2, name: "B"}

Create a greeting function:

1. `greet(name)` prints "Hello, [name]".
2. Give `name` a default value of "Guest" if not provided.
3. Call the function without arguments.

function greet(name = "Guest") {
    console.log(`Hello, ${name}`);
}

greet(); // Hello, Guest

Calculate the sum of numbers:

1. You have `prices = [10, 20, 30]`.
2. Use `reduce` to calculate the total sum.

const prices = [10, 20, 30];
const total = prices.reduce((sum, price) => sum + price, 0);

console.log(total); // 60

Extract values from an array:

1. You have `coords = [10, 20]`.
2. Extract the values into `x` and `y` using destructuring.

const coords = [10, 20];
const [x, y] = coords;

console.log(x, y);

Create an object using shorthand:

1. You have `name = "Sara"` and `age = 25`.
2. Create `person` without repeating property names (shorthand properties).

const name = "Sara";
const age = 25;

const person = { name, age }; // instead of { name: name, age: age }

console.log(person);