Array, if, while, for

vancouver·2023년 4월 26일

javascript이해하기

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2/22

내 풀이

function isLeap(year) {

if (year % 4 === 0 ){
    console.log("Leap year.");
} 
if (year % 100 !== 0){
    console.log("Not leap year.")
}
if (year % 400 === 0){
    console.log("Leap year.")
}
}

정답

function isLeap(year) {
  
  if(year % 4 === 0) {
    if(year % 100 === 0) {
      if(year % 400 === 0) {
        return "Leap year.";
     }  else {
         return "Not leap year.";
     }
    } else{
       return "Leap year.";
    }
  }else {
    return "Not leap year.";
  }
}

includes

var guestList = ["Angela", "Jack", "Pam", "James", "Lara", "Jason"];

var guestName = prompt("what is you name?");

    guestList.includes(guestName)

배열안에 이름을 적으면 참, 아니면 거짓 출력

if else

var output = [];
var count = 1;
function fizzBuzz() {

    if (count % 3 === 0 && count % 5 === 0){
        output.push("FizzBuzz");
}
    
    else if (count % 3 === 0) {
        output.push("Fizz");
}    
    else if (count % 5 === 0) {
        output.push("Buzz");
}
    else {
        output.push(count);         
}

count++;

    console.log(output);
}

3의 배수는 Fizz
5의 배수는 Buzz
3,5의 배수가 겹칠때는 FizzBuzz를 나열하는 코드

else if문의 순서를 잘봐야한다.

점심내기

function whosPaying(names) {

    var numberOfPeople = names.length;
    var randomPersonPosition = Math.floor(Math.random() * numberOfPeople);
    var randomPerson = names[randomPersonPosition];

return randomPerson + " is going to buy lunch today!";

}

while

var i = 1;
while (i<2) {
  console.log(i) ;
  i++;
}

While FizzBuzz

var output = [];
var count = 1;
function fizzBuzz() {

  	while(count <= 100) {
    if (count % 3 === 0 && count % 5 === 0){
        output.push("FizzBuzz");
}
    
    else if (count % 3 === 0) {
        output.push("Fizz");
}    
    else if (count % 5 === 0) {
        output.push("Buzz");
}
    else {
        output.push(count);         
}

count++;
    }
    console.log(output);
}

100번째에 도달할때까지 반복.

beer

var beerNumber = 99
    while(beerNumber >= 1) {
        var bottleWord = "bottles";

        if (beerNumber === 1) {
           bottleWord = "bottle";
        }
console.log(beerNumber + " " + bottleWord + " of beer on the wall");
console.log(beerNumber + " " + bottleWord + " of beer,");
console.log("Take one down, pass it around,");
beerNumber--;
console.log(beerNumber + " " + bottleWord + " of beer on the wall.");
}

for

기초

	 ↓시작  ↓끝  ↓바뀌는조건
for (i=0; i<2; i++) {

}

while문

var i = 1;
while (i<2) {
  console.log(i) ;
  i++;
}

for문으로 간략화.

for (var i=1; i<2; i++) {
  console.log(i);
}

// for...in
const yuJin = {
  name: `안유진`,
  year: 2003,
  group: `아이브`,
};

for (let key in yuJin) {
  console.log(key); // name year group
}

const iveMembersArray = [`안유진`, `가을`, `레이`, `장원영`, `리즈`, `이서`];

for (let key in iveMembersArray) {
  console.log(key); // 0 1 2 3 4 5
  console.log(`${key}: ${iveMembersArray[key]}`); //0: 안유진 1: 가을 2: 레이 3: 장원영 4: 리즈 5: 이서
}

// for...of
for (let value of iveMembersArray) {
  console.log(value); //`안유진`, `가을`, `레이`, `장원영`, `리즈`, `이서`
}

// while
let number = 10;
while (number < 10) {
  number++;
}
console.log(number); // 10

// do..while
number = 0;

do {
  number++;
} while (number < 10);

console.log(number); // 10

// break
for (let i = 0; i < 10; i++) {
  if (i === 5) {
    break;
  }
  console.log(i); // 0 1 2 3 4
}
console.log(`----------------`);

number = 0;
while (number < 10) {
  if (number === 5) {
    break;
  }
  number++;
  console.log(number); // 1 2 3 4 5
}
// continue (조건에 들어간 경우한걸 제외한 나머지를 반복문설정)
console.log(`----------------`);

number = 0;
while (number < 10) {
  number++;
  if (number === 5) {
    continue;
  }
  console.log(number); // 1 2 3 4 6 7 8 9 10
}

For FizzBuzz

var output = [];

function fizzBuzz() {

  	for(var count = 1; count <= 100 count++;) {
    if (count % 3 === 0 && count % 5 === 0){
        output.push("FizzBuzz");
}
    
    else if (count % 3 === 0) {
        output.push("Fizz");
}    
    else if (count % 5 === 0) {
        output.push("Buzz");
}
    else {
        output.push(count);         
}

}
    console.log(output);
}

fibonacci Generator

function fibonacciGenerator(n) {
  if (n === 1) {
    var output = [];
    output = [0];
  } else if (n === 2) {
    output = [0, 1];
  } else {
    output = [0, 1];
    for (var i = 2; i < n; i++) {
      output.push(output[output.length - 2] + output[output.length - 1]);
    }
  }
  return output;
}