Array 배열

// 1. Declaration
const arr1 = new Array();
const arr2 = [1, 2];

// 2. Index position
const fruits = ['🍎', '🍌'];
console.log(fruits);
console.log(fruits.length);
console.log(fruits[0]);
console.log(fruits[1]);
console.log(fruits[2]);
console.log(fruits[fruits.length - 1]);

console.clear();
// 3. Looping over an array
// print all fruits
// a. for
for (let i = 0; i < fruits.length; i++) {
    console.log(fruits[i]);
}

// b. for of
for (let fruit of fruits) {
    console.log(fruit);
}

// c. forEach
fruits.forEach((fruit) => console.log(fruit));

// 4. Addtion, deletion, copy
// push: add an item to the end
fruits.push('🍓', '🍑');
console.log(fruits);

// pop: remove an item from the end
fruits.pop();
fruits.pop();
console.log(fruits);

// unshift: add an item to the begining
fruits.unshift('🍓','🍋');
console.log(fruits);

// shift: remove an item from the begining
fruits.shift();
fruits.shift();
console.log(fruits);

// note!! shift, unshift are slower than pop, push
// splice: remove an item by index position
fruits.push('🍓', '🍑','🍋');
console.log(fruits);
fruits.splice(1, 1) //index값만 지정할경우 지정된 index값 뒤로는 다 지워짐
console.log(fruits);
fruits.splice(1, 0, '🍏', '🍉');
console.log(fruits);

// combine two arryas
const fruits2 = ['🍐', '🥥'];
const newFruits = fruits.concat(fruits2);
console.log(newFruits);

// 5. Searching
// indexOf: find the index
console.clear();
console.log(fruits);
console.log(fruits.indexOf('🍎'));
console.log(fruits.indexOf('🍉'));
console.log(fruits.indexOf('🥥'));

// includes
console.log(fruits.includes('🍉'));
console.log(fruits.includes('🥥'));

// lastIndexOf
console.clear();
fruits.push('🍎');
console.log(fruits);
console.log(fruits.indexOf('🍎'));
console.log(fruits.lastIndexOf('🍎'));