'use strict'; // ! Array console.log('--- 1. Declaration ---'); // ! 1. Declaration const arr1 = new Array(); const arr2 = [1, 2]; console.log(arr1); console.log(arr2); console.log('--- 2. Index position ---'); // ! 2. Index position const fruits = ['사과', '바나나']; console.log(fruits); console.log(fruits.length); // object에서는 string type의 key를 통해 접근했다면, array는 Index로 접근 console.log(fruits[0]); console.log(fruits[1]); console.log(fruits[2]); console.log(fruits[fruits.length - 1]); // array의 마지막 값을 찾을 때 사용 console.log('--- 3. Looping over an array ---'); // ! 3. Looping over an array // print all fruits // # for for (let i = 0; i < fruits.length; i++) { console.log(`for: ${fruits[i]}`); } // # for of for (let fruit of fruits) { console.log(`for of: ${fruit}`); } // # forEach(callbackfn) fruits.forEach((fruit) => // anonymous function는 arrow function 가능 console.log(`forEach: ${fruit}`) ); console.log('--- 4. Addition, Deletion, Copy ---'); // ! 4. Addition, Deletion, Copy // @ push: add an item to the end fruits.push('딸기', '복숭아'); console.log(fruits); // @ pop: remove an item from the and fruits.pop(); fruits.pop(); console.log(fruits); // @ unshift: add an item to the beginning fruits.unshift('딸기', '레몬'); console.log(fruits); // @ shift: remove an item from the beginning fruits.shift(); fruits.shift(); console.log(fruits); // note) shift, unshift are slower than pop, push // why? 전체 data가 움직여야하기 때문!! // @ splice: remove an item by index position fruits.push('딸기', '복숭아', '레몬'); console.log(fruits); fruits.splice(1); // 지정한 index부터 모든 data 삭제 console.log(fruits); fruits.push('바나나', '딸기', '복숭아', '레몬'); console.log(fruits); fruits.splice(1, 1); // 바나나 삭제 console.log(fruits); // 1 index(딸기) 삭제 후 1 index부터 '아오이 사과', '수박' 추가 fruits.splice(1, 1, '아오이 사과', '수박'); console.log(fruits); // @ concat: combine two arrays const fruits2 = ['키위', '코코넛']; const NewFruits = fruits.concat(fruits2); console.log(NewFruits); console.log('--- 5. Searching ---'); // ! 5. Searching // @ IndexOf: find the index console.log(fruits); console.log(fruits.indexOf('사과')); console.log(fruits.indexOf('수박')); console.log(fruits.indexOf('코코넛')); // @ includes console.log(fruits.includes('수박')); console.log(fruits.includes('코코넛')); // @ lastIndexOf fruits.push('사과'); console.log(fruits); console.log(fruits.indexOf('사과')); // 0, 5 index에 '사과'가 있지만, 처음 나오는 0 index만 출력 console.log(fruits.lastIndexOf('사과')); // 0, 5 index에 '사과'가 있지만, 마지막에 나오는 0 index만 출력