유용한 10가지 배열 함수들

// Q1. make a string out of an array
{
    const fruits = ['apple', 'banana', 'orange'];
    const result = fruits.join(' ');
    console.log(result);
}

// Q2. make an array out of a string
{
    const fruits = '🍎, 🥝, 🍌, 🍒';
    const result = fruits.split(', ');
    console.log(result);
}

// Q3. 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);
}

// Q4. make new array without the first two elements
{
    const array = [1, 2, 3, 4, 5];
    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),
];

// Q5. find a student with the score 90
{
    const result = students.find((student) => student.score === 90);
    console.log(result);
}

// Q6. make an array of enrolled students
{
    const result = students.filter((student) => student.enrolled);
    console.log(result);
}

// Q7. make an array containing only the students' scores
// result should be: [45, 80, 90, 66, 88]
{
    const result = students.map((student) => student.score);
    console.log(result);
}

// Q8. check if there is a student with the score lower than 50
{
    const result = students.some((student) => student.score < 50);
    console.log(result);

    const result2 = !students.every((student) => student.score >= 50);
    console.log(result2);
}

// Q9. compute students' average score
{
    const result = students.reduce((prev, curr) => prev + curr.score, 0);
    console.log(result / students.length);
}

// Q10. 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);

    const result2 = students
    .map((student) => student.score)
    .filter((score) => score >= 50)
    .join(', ');
    console.log(result2);
}

// 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);

    const result2 = students.map((student) => student.score)
    .sort((a, b) => b - a)
    .join(', ');
    console.log(result2);
}

 

 

 

참고

youtube 드림코딩 by 엘리

https://www.youtube.com/watch?v=3CUjtKJ7PJg&list=PLv2d7VI9OotTVOL4QmPfvJWPJvkmv6h-2&index=9