노력이 좋아서

<step58>'js_복습(1)'

zoaseo 2022. 6. 13. 17:17 
<!DOCTYPE html>
<html lang="en">
<head>
    <meta charset="UTF-8">
    <meta http-equiv="X-UA-Compatible" content="IE=edge">
    <meta name="viewport" content="width=device-width, initial-scale=1.0">
    <title>Document</title>
</head>
<body>
    <script>
        //배열선언
        let arr = new Array();
        let arr2 = [];
        let arr3 = [1,2,3,4,5];
        console.log(arr3[0]);
        console.log(arr3[1]);
        let fruits = ['🍉','🍊','🥝','🍓'];
        fruits.push('🍐');
        fruits.unshift('🍇');
        console.log(fruits);
        fruits.shift();
        fruits.pop();
        fruits.forEach((item, index)=>{
            console.log(item, index);
        })
        for(let i=0; i<fruits.length; i++){
            console.log(fruits[i], i);
        }
        for(let value of fruits){
            console.log(value);
        }
        //배열 메서드
        //pop(), push(), shift(), unshift()
        //join(), indexOf(), includes(), splice(), slice()
        //substr(), map(), find(), filter(), reduce()
        let arrStr = fruits.join("");
        console.log(arrStr);
        console.log(typeof(arrStr));
        console.log(fruits.indexOf('🍒'));  //-1
        console.log(fruits.indexOf('🍉'));  //0
        console.log(fruits.includes('🍒'));  //false
        console.log(fruits.includes('🍉'));  //true
        let scores = [80,60,70,90,95];
        let sc2 = scores.map(score=>{
            return score+10;
        })
        console.log(sc2);
        let sc3 = scores.filter(score=>{
            return score>=70;
        })
        console.log(sc3);
        let sc4 = scores.find(score=>{
            return score>=70;
        })
        console.log(sc4);
        let sum = scores.reduce((pre,cur)=>{
            return pre+cur;
        },0)
        console.log(sum);
        let avg = sum/scores.length;
        console.log("점수 배열의 평균은 "+ avg +"입니다.");
        console.log(`점수 배열의 평균은 ${avg}입니다.`);
        //2차원 배열 
        let multyArr = [[1,10],[2,20],[3,30],[4,40]];
        console.log(multyArr[0][1]);
        console.log(multyArr[0][0]);
        multyArr.forEach(item=>{
            item.forEach(i=>{
                console.log(i);
            })
        })
        //set
        let set = new Set();  //중복 허용x
        set.add(1);
        set.add(2);
        set.add(3);
        set.add(4);
        set.add(5);
        set.add(2);
        console.log(set);
        let set2 = new Set();
        let green = { name: 'green'};
        let blue = { name: 'blue'};
        let pink = { name: 'pink'};
        set2.add(green);
        set2.add(blue);
        set2.add(pink);
        console.log(set2);
        set2.forEach((value,index)=>{
            console.log(`value는 ${value}이다.`);
            console.log(`index는 ${index}이다.`);
        })
        set.forEach((value,index)=>{
            console.log(`value는 ${value}이다.`);
            console.log(`index는 ${index}이다.`);
        })
        let numSet = new Set([1,2,3,4,5,5,6,7,7,6,3,2]);
        console.log(numSet);
        let newArr = [...numSet];
        console.log(newArr);
    </script>
</body>
</html>