const obj = {
title: 'The Title',
name: 'Jane',
contents: 'Nothing to say'
};
for (let key in obj) {
if ( key === "title" || key === "name" ){
obj[key] = obj[key].toUpperCase()
// obj[key], μ¦ valueμ λ€μ κ°μ ν λΉμμΌμΌ ν¨
}
}
console.log(obj)
//{ title: 'THE TITLE', name: 'JANE', contents: 'Nothing to say' }
// ======= 1 =======
const obj = {
title: 'The Title',
name: 'Jane',
contents: 'Nothing to say'
};
const arr = Object.entries(obj)
for (let element of arr){
console.log(element[0])
// 'title'
// 'name'
// 'contents'
if (element[0]==="title" || element[0]==="name"){
element[1] = element[1].toUpperCase()
console.log(element[1])
// 'THE TITLE'
// 'JANE'
}
}
console.log(arr);
// ======= 2 =======
const arr = [11, 22, 33, 44, 55];
let sum = 0;
for (let element of arr){
sum += element
}
//whileλ¬Έμ μ΄μ©νλ€λ©΄?
// let i = 0;
// while (i< arr.length){
// sum += arr[i]
// i += 1
// }
console.log(sum);
// 165
for (let i = 0; i<3; i++){
console.log("hi")
}
//result: 'hi'
// 'hi'
// 'hi'
let i = 0
μ΅μ΄μ: λ°λ³΅λ¬Έμ μ²μ μ€νν λ μ μΈ / μ΄λμλΆν° μμνλμ§λ₯Ό κ²°μ νλ μμμ
--> iλ₯Ό 0λΆν° μμνκ² λ€
i<3
쑰건μ: λ°λ³΅λ¬Έμ μ€ννλ 쑰건μ μ€μ / ν΄λΉ 쑰건μμ΄ trueμΌλλ§ λ‘μ§μ μ€ν
--> iκ° 3μ΄ λκΈ° μ κΉμ§λΌλ 쑰건μ κ±°λ κ²
i++
μ¦κ°μ: λ°λ³΅λ¬Έμ μ€νν λλ§λ€ μ΅μ΄μμ μ¦κ° / λ°λ³΅λ¬Έμ μ€ν νμλ₯Ό μ‘°μ ν μ μλ€
--> iλ₯Ό νλμ© μ¬λ¦¬κ² λ€
for (let i = 0; i < 5; i++){
if (i===2){
break
}
console.log(i)
}
//result: 0
// 1
for (let i = 0; i < 5; i++){
if (i===2){
continue
}
console.log(i)
}
//result: 0
// 1
// 3
// 4
str = 'abc'
for (let key in str){
console.log(key)
// '0' '1' '2' μΆλ ₯
// λ¬Έμμ΄μ λ°°μ΄κ³Ό λμΌνκ² μΈλ±μ€ κ°μΌλ‘ μΆλ ₯μ΄ κ°λ₯ν¨
console.log(str[key])
// 'a' 'b' 'c'
// strμ λν keyλ₯Ό λ½μμλ¬λΌκ³ νλκ±°κΈ° λλ¬Έ
}
obj = {
name: "μ² μ",
age: 12
}
for (let key in obj){
console.log(obj[key])
}
//result: "μ² μ"
// 12
str = "abc"
for (let data of str){
console.log(data)
}
// result: 'a'
// 'b'
// 'c'
for (let i = 0; i<str.length; i++){
console.log(str[i])
}
// result: 'a'
// 'b'
// 'c'
// =========== λ°°μ΄ μμ κ° μΆλ ₯νκΈ° ===========
arr = ["a","b","c"]
arr.forEach(function(el){
console.log(el)
})
//result: 'a'
// 'b'
// 'c'
arr.forEach(el => {
console.log(el)
})
//result: 'a'
// 'b'
// 'c'
// =========== λ°°μ΄ μμ μλ μ μ λΆ λνκΈ° ===========
arr = [1,2,3,4,5,6,7,8,9,10]
answer = 0
arr.forEach(el => {
answer = answer + el
})
console.log(answer) // 55
let count = 0;
while(count !== 5){
console.log(count)
count++
}
//result: 0
// 1
// 4
// 2
// 3
// 4
function sum(num){
let count = 0;
for (let i = 1 ; i <= num ; i++){
count += i
}
return count
}
sum(5) // 15
function countLetter(str){
let count = 0;
for (let i = 0; i<str.length; i++){
if (str[i]==="a" || str[i]==="A"){
// console.log(str[i], i)
count++
}
}
return count
}
countLetter("I am from Korea") //2
countLetter("A day without laughter is a day wasted.") //6
// ============ or μ λΆ λ€ μλ¬Έμλ‘ λ°κΏμ νμΈν΄λ΄κΈ° ============
// κ²μ¦ μ‘°κ±΄μ΄ μ€μ΄λλ ν¨μ¨μ± μ¦κ°
function countLetter(str){
let count = 0;
str = str.toLowerCase() // μλ¬Έμλ‘ λ³ν: toLowerCase()
for (let i = 0; i<str.length; i++){
if (str[i]==="a"){
count++
}
}
return count
}
countLetter("I am from Korea") //2
countLetter("A day without laughter is a day wasted.") //6
function makeNumber(num){
let str = ''
for (let i = 1; i<=num; i++){
str += String(i)
if (i !== num){ //iμ num(μ¦ λ§μ§λ§ μ)μ λμΌν λλ hyphen μ μΈ
str += "-"
}
}
return str
}
makeNumber(5) // '1-2-3-4-5'
makeNumber(7) // '1-2-3-4-5-6-7'
function makeOdd(num){
let str = ''
for (let i = 1; i<= num; i++){
if (i % 2 === 1){
str += i
}
}
return str
}
makeOdd(5) // '135'
makeOdd(7) // '1357'
function bigNum(str){
let biggest = Number(str[0])
for (let i = 0; i<str.length; i++){
console.log(str[i], biggest)
if (biggest < Number(str[i])){
biggest = Number(str[i])
}
}
return biggest
}
bigNum("129638") // 9