JS의 내장함수

프로그래머스를 풀면서 사용했던 내장함수들을 정리해보았다.

console.log('repeat')
const rowstar = "*".repeat(5)
console.log(rowstar)

repeat
*****

---

console.log('Number')
let somestr = "5500"
console.log(typeof(Number(somestr)))

Number
number

---

console.log('includes');

let arr = [1, 2, 3, 4, 5, "우산"];

console.log(arr.includes('우산'));
console.log(arr.includes(3));

includes
true
true

---

console.log('push');

let arr = [1, 2, 3, 4, 5];
arr.push('바지');

console.log(arr);

push
[ 1, 2, 3, 4, 5, '바지' ]

---

console.log('Number.isInteger')

console.log(Number.isInteger(3.4))
console.log(Number.isInteger(4))

Number.isInteger
false
true

---

console.log('sort를 사용한 내림차순, 올림차순')

let arr =[1, 4, 3, 6, 2, 4, 77, 31]
arr.sort(function compare(a, b) {
    return a - b;});
console.log(arr)

arr.sort(function compare(a, b) {
    return b - a;});
console.log(arr)

sort를 사용한 내림차순, 올림차순
[
  1, 2,  3,  4,
  4, 6, 31, 77
]
[
  77, 31, 6, 4,
   4,  3, 2, 1
]

---

console.log('isNaN')

console.log(isNaN('a'))
console.log(isNaN(44))

isNaN
true
false