const numbers = [1, 2, 3, 4]
const fruits = ['Apple', 'Banana', 'Cherry']
const a = numbers.map(number => number < 3)
console.log(a) //(4) [true, true, false, false]
const b = numbers.filter(number => number < 3)
console.log(b) //(2) [1, 2]
console.log(numbers) //(4) [1, 2, 3, 4]
const numbers = [1, 2, 3, 4]
const fruits = ['Apple', 'Banana', 'Cherry']
const a = fruits.find(fruit => /^C/.test(fruit)) //C로시작하는
console.log(a) //Cherry
const b = fruits.findIndex(fruit => /^C/.test(fruit))
console.log(b) //2
const numbers = [1, 2, 3, 4]
const fruits = ['Apple', 'Banana', 'Cherry']
const a = numbers.includes(3)
console.log(a) //true
const b = fruits.includes('hyerin')
console.log(b) //false
const numbers = [1, 2, 3, 4]
const fruits = ['Apple', 'Banana', 'Cherry']
numbers.push(5)
console.log(numbers) //(5) [1, 2, 3, 4, 5]
numbers.unshift(0)
console.log(numbers) //(6) [0, 1, 2, 3, 4, 5]
const numbers = [1, 2, 3, 4]
const fruits = ['Apple', 'Banana', 'Cherry']
numbers.reverse()
fruits.reverse()
console.log(numbers) //(4) [4, 3, 2, 1]
console.log(fruits) //(3) ["Cherry", "Banana", "Apple"]
const numbers = [1, 2, 3, 4]
const fruits = ['Apple', 'Banana', 'Cherry']
numbers.splice(2, 1)
console.log(numbers) //(3) [1, 2, 4]
numbers.splice(2, 0, 999)
console.log(numbers) //(4) [1, 2, 999, 4]
numbers.splice(2, 1, 99)
console.log(numbers) //(4) [1, 2, 99, 4]
fruits.splice(2, 0, 'Orange')
console.log(fruits) //(4) ["Apple", "Banana", "Orange", "Cherry"]