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8. Array APIs 본문

JavaScript & TypeScript

8. Array APIs

kingsubin 2020. 11. 14. 14:24

Quiz

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

// 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); // [5, 4, 3, 2, 1]
console.log(array); // [5, 4, 3, 2, 1]

// Q4. make new array without the first two elements
const array = [1, 2, 3, 4, 5];
const result = array.slice(2);
console.log(result); // [3, 4, 5]
console.log(array); // [1, 2, 3, 4, 5]

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 === true);
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); // true
const result2 = students.every((student) => student.score >= 50);
console.log(result2); // true

// 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)
.filter(score => score >= 50)
.join();
console.log(result); // 50점 이상

// 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);

 

  • join
  • split
  • reverse
  • slice
  • find
  • filter
  • map
  • some
  • every
  • reduce

 

 

 

 

 


※출처

www.youtube.com/channel/UC_4u-bXaba7yrRz_6x6kb_w

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