JS [array]

'use strict'

// Array

// 1. Declaration

const arr1 = new Array();

const arr2 =[1,2];

// 2. Index position

const fruits =['apple','banana'];

console.log(fruits);

console.log(fruits.length);

console.log(fruits[0]);

// 3. Looping over an array

// 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. Addition, deletion, copy

// push: add an item to the end

fruits.push('starwberry','peach');

//pop: remove an item from the end

fruits.pop();

fruits.pop();

console.log(fruits);

//unshift: add an item to the beginning

fruits.unshift('lemon','blueberry');

console.log(fruits);

//shift: remove an item from the beginning

fruits.shift();

console.log(fruits);

// note!! shift, unshift are slower than pop, push

// splice: remove an item by index position

fruits.push('peach','lemon','blueberry');

console.log(fruits);

fruits.splice(1,1); // index 1 삭제

console.log(fruits)

fruits.splice(1,1,'melon','watermelon'); // index 1 삭제 후, melon watermelon 추가

//combine two arrays

const fruits2=['pear','coconut'];

const newFruits=fruits.concat(fruits2)

fruits.pop();

// 5. searching

console.log(fruits)

console.log(fruits.indexOf('melon'));  

console.log(fruits.indexOf('potato'));  //없으면 -1 리턴

//includes

console.log(fruits.includes('apple')); //있으면 true 리턴

console.log(fruits.includes('potato')); //없으면 false 리턴

// lastIndexOf

fruits.push('apple');

console.log(fruits);

console.log(fruits.lastIndexOf('apple')); // 마지막 원소의 index 리턴

console.log(fruits.toString());

// console.log(fruits.join('j'));

fruits.reverse();

console.log(fruits);