Array พื้นฐาน

const cars = ["Toyota", "Honda", "BMW", "Tesla", "Lexus"];

// Index of the first element is 0 (zero)
console.log(cars[0]);                 // Toyota
console.log(cars[1]);                 // Honda
const index = 0;
console.log(cars[index]);             // Toyota

// Trying to access element that does not exist
console.log(cars[9]);                 // undefined

// Using arr.length property
console.log(cars.length);             // 5
console.log(cars[cars.length]);       // undefined
console.log(cars[cars.length - 1]);   // Lexus

const cars = ["Toyota", "Honda", "BMW", "Tesla", "Lexus"];

cars.push("Suzuki")   // [..., "Lexus", "Suzuki"]
cars.pop()            // เอา "Suzuki" ออก
cars.pop()            // เอา "Lexus" ออก

const selectedCar = cars.shift()   // selectedCar = "Toyota"
cars.unshift("Lambo")              // ["Lambo", "Honda", ...]

const cars = ["Honda", "BMW"];
const user = { name: "John Ive", age: 33 }
const isAlive = true;
const msg = "Running..."

console.log(typeof cars)             // object
console.log(typeof user)             // object
console.log(typeof isAlive)          // boolean
console.log(typeof msg)              // string
console.log(Array.isArray(cars))     // true
console.log(Array.isArray(user))     // false

const cars = ["Toyota", "Honda", "BMW", "Tesla", "Lexus"];

// แบบที่ 1: for กับ length
for (let i = 0; i < cars.length; i++) {
  console.log(i, "is", cars[i]);
}

// แบบที่ 2: forEach
cars.forEach((el, idx, arr) => {
  console.log(el, idx, arr);
});

const cars = ["Toyota", "Honda", "BMW", "Tesla", "Lexus"];
const [car1, car2] = cars;      // car1 = "Toyota", car2 = "Honda"

const [, second] = cars;        // ข้ามตัวแรก: second = "Honda"
const [,, third] = cars;        // ข้ามสองตัว: third = "BMW"

const fruits = ["Banana", "Apple"]
const fruits2 = ["Orange"]
const fruits3 = ["Pineapple", "Mango"]

const allFruits = fruits.concat(fruits2, fruits3)
// ["Banana", "Apple", "Orange", "Pineapple", "Mango"]

allFruits.join(" | ")            // "Banana | Apple | Orange | Pineapple | Mango"

allFruits.includes("Banana")     // true
allFruits.includes("banana")     // false  ← case-sensitive
allFruits.includes("Banana", 1)  // false  ← เริ่มค้นที่ index 1 จึงไม่เจอตัวที่ index 0

let newFruits = allFruits.slice(2)
// ["Orange", "Pineapple", "Mango"]   allFruits ไม่เปลี่ยน

newFruits = allFruits.slice(2, allFruits.length)   // ผลเหมือนกัน

const q = ["A", "B", "C"];
q.push("D");
const a = q.shift();
q.unshift("Z");
const b = q.pop();
const n = q.length;