JS [array API]

// 01. make a string out of an array O

{

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

    //console.log(fruits.toString());

    const result = fruits.join();

    console.log(result);

}

// 02. make an array out of a string  X

{

    const fruits='apple,cherry,banana,coconut';

    const result = fruits.split(',');

    console.log(result)

}

// 03. make this array look like this: [5,4,3,2,1]

{

    const array = [1,2,3,4,5];

    const result = array.reverse();

    console.log(result);

    console.log(array);

}

// 04. make this array without the first tow elements O

{  

    const array=[1,2,3,4,5];

    // result=array.filter((item)=>item>2);

    // console.log(result);

    // splice는 배열 자체 수정

    // slice는 새로운 배열을 생성

    const result = array.slice(2,5);

    console.log(result);

}

class Student{

    constructor(name,age,enrolled,score){

        this.name=name;

        this.age=age;

        this.enrolled=enrolled;

        this.score=score;

    }

}

const students = [

    new Student('A',29,true,45),

    new Student('B',28,false,80),

    new Student('C',30,true,90),

    new Student('D',40,false,66),

    new Student('E',18,true,88),

]

// 05. find a studnet with the score 90 X

{

    // const result = students.find(function(student,index){

    //     return student.score===90;

    // });

    const result = students.find((student)=> student.score===90);

    console.log(result);

}

// 06 make an array of enrolled students

{

    const result = students.filter((student)=>student.enrolled===true);

    console.log(result);

}

// 07. make an array containing only the student;s scores result should be: [45,80,90,66,88] X

{

// 배열의 각 요소를 하나씩 꺼내 mapping

    const result =students.map((student)=>student.score)

    console.log(result);

}

// 08. check if there is a student with the score lower than 50 O

{

    const result = students.some((student)=> student.score<50);

    console.log(result);

    const result2 = students.every((student)=>student.score>=50);

    console.log(!result2);

}

// 09. compute student's average score X

{

    // 배열을 순차적으로 돌면서 값을 누적하는 API

    const result = students.reduce((prev,curr)=>prev+curr.score,0);

    console.log(result /students.length);

    //reduce right은 배열의 반대쪽(오른쪽)부터 시작

}

// 10. make a string containing all the scores

// result should be: '45, 80, 90, 66 ,88'

{

    const result =students.map((student)=>student.score).join();

    console.log(result);

}

// bonus do Q10 sorted in ascending order

// result should be: '45, 66, 80, 88, 90'

{

    const result=students.map((student)=>student.score).sort((a,b)=>a-b).join();

    console.log(result);

}