[CODECADEMY] 코드카데미 CODE CHALLENGES: JAVASCRIPT FUNDAMENTALS

 

 

1. canIVote()

 

canIVote의 인자(parameter)을 age로 잡아줘야함

const canIVote = (age)=>{ 
  if (age >= 18){
    return true;
  } else if (age < 18){
    return false;
  }
};

console.log(canIVote(19)); //print >> true
console.log(canIVote(18));//print >> true
console.log(canIVote(5));//print >> false

 

---

 

2. agreeOrDisagree()

const agreeOrDisagree=(stringA="",stringB="")=>{
 if (stringA===stringB){
  return 'You agree!';
 } else {
   return 'You disagree!';
 }
}

 console.log(agreeOrDisagree("yep", "yep")); 
 // print >> 'You agree!'

---

3. lifePhase()

 

3-1. if 문법 사용

const lifePhase=(age)=>{
  if(age>=0 &&age<= 3) {
    return 'baby';
  } else if (4<= age && age<= 12) {
   return 'child'; 
  } else if (13<= age && age<= 19) {
   return 'teen';
  } else if (20<= age && age <= 64) { 
   return 'adult';
  } else if (65<= age && age<= 140) {
   return 'senior citizen'; 
  } else if (0> age || age >=140) {
   return 'This is not a valid age';
  }
}


console.log(lifePhase(15))
// print >> teen

---

 

 

3-1. switch statement사용

 

switch의 variable을 true로 두기! 

const lifePhase=(age)=>{
  switch(true){
   case age >= 0 && age<= 3:
   return 'baby';
   case 4<= age && age<= 12:
   return 'child';
   case 13<= age && age<= 19:
   return 'teen';
   case 20<= age && age <= 64:
   return 'adult';
   case 65<= age && age<= 140:
   return 'senior citizen';
   case 0> age || age >=140:
   return 'This is not a valid age';
  };
}

console.log(lifePhase(18)) 
//print >>teen

---

 

 

4. finalGrade()

 

const finalGrade=(midterm,final ,homework)=>{
 const average=(midterm+final+homework)/3;
 if ((midterm< 0 || midterm> 100)||(final< 0 || final > 100)|| (homework < 0 || homework >100)) {
   return 'You have entered an invalid grade.';
 } else if (average>= 0 && average<= 59){
   return 'F'
 } else if (average>= 60 && average<= 69){
   return 'D'
 } else if (average>= 70 && average<= 79){
   return 'C'
 } else if (average>= 80 && average<= 89){
   return 'B'
 } else if (average>= 90 && average<= 100){
   return 'A'
}}


console.log(finalGrade(99, 92, 95)) // print 'A'

 

 

---

 

5. reportingForDuty()

const reportingForDuty= (rank,lastName) => {
return `${rank} ${lastName} reporting for duty!` };

 console.log(reportingForDuty('Private','Fido'));
 // print >> Private Fido reporting for duty!

 

 

---

 

6. Fix The Broken Code

 

주사기는 1~6까지의 숫자가 있음.

Math.random()*7을 쓰면 0을 포함한 0~6까지의 숫자가 나오기 때문에 적절하지 않음. 

따라서 Math.random()*6 을 이용하여 0~5까지의 숫자를 랜덤하게 추출한 다음 +1을 하여 1~6의 숫자를 만들어 줌. 

하지만 Math.random()은 소수를 추출하기 때문에 정수를 추출하기 위해 Math.floor()로 전체를 감싸준다. 

 

const rollTheDice = () => {

    let die1 = Math.floor(Math.random() * 6 + 1)
    let die2 = Math.floor(Math.random() * 6 + 1)
    return die1 + die2
}

console.log(rollTheDice());

 

---

 

7. calculateWeight()

 

7-1. if 문

const calculateWeight= (earthWeight,planet='') => {
  if (planet==='Mercury') {
    return earthWeight * 0.378;
  } else if (planet==='Venus') {
  return earthWeight * 0.907;
  } else if (planet==='Mars') {
  return earthWeight * 0.377;
  } else if (planet==='Jupiter') {
  return earthWeight * 2.36;
  } else if (planet==='Saturn') {
  return earthWeight * 0.916;
  } else {
    return 'Invalid Planet Entry. Try: Mercury, Venus, Mars, Jupiter, or Saturn.';
  }

}

 console.log(calculateWeight(100, 'Jupiter')) 
 // print >> 236

 

7-2. switch 문

const calculateWeight= (earthWeight,planet='') => {
  switch (true) {
    case planet==='Mercury':
    return earthWeight * 0.378;
    case planet==='Venus': 
    return earthWeight * 0.907;
    case planet==='Mars':
    return earthWeight * 0.377;
    case planet==='Jupiter' : 
    return earthWeight * 2.36;
    case planet==='Saturn':
    return earthWeight * 0.916;
    default: 'Invalid Planet Entry. Try: Mercury, Venus, Mars, Jupiter, or Saturn.';
  }

}

---

 

8. truthyOrFalsy()

const truthyOrFalsy=(value)=> {
    if (value) {
       return true;
    } else {
      return false ;
    }
}

console.log(truthyOrFalsy('12')) 
//print true

console.log(truthyOrFalsy(0)) 
//print false

---

 

9. numImaginaryFriends()

Math.round를 사용하여 소숫점 없애기

const numImaginaryFriends=(actualFreinds)=>{
 return Math.round(actualFreinds * 0.33);
}


console.log(numImaginaryFriends(18)) 
// print >> 6

---

 

10. sillySentence()

const sillySentence=(adjective,verb,noun) => {
  return `I am so ${adjective} because I ${verb} coding! Time to write some more awesome ${noun}!` ;
}

console.log(sillySentence('excited', 'love', 'functions')) 
// print >> I am so excited because I love coding! Time to write some more awesome functions!

---

 

11. howOld()

 

 

현재날짜 불러오기 (currentDate)

  let currentDate = new Date();

 현재 날짜의 년도 불러오기 (currentDate.getFullYear)

  let currentDate = new Date();
  let theCurrentYear = currentDate.getFullYear();

현재 날짜의 시간 불러오기 (currentDate.getHours)

  let currentDate = new Date();
  let theCurrentHour = currentDate.getHours();

 

와 같은 방법으로 분,초를 불러올 수 있다. 

---

절대값 구하기 (Math.abs)

 

abs 는 입력받은 숫자의 부호를 제거하고 그 결과를 리턴해주는 함수 = 절대값

 Math.abs([대상 숫자]);

 

var test = -123;
test = Math.abs(test);

//print >> 123

---

 

 

완성코드

const howOld=(age,year)=>{
  let currentDate = new Date();
  let theCurrentYear = currentDate.getFullYear();

  const yearDiffefence = year-theCurrentYear;
  const newAge = age + yearDiffefence;

  if (newAge > age) {
    return `You will be ${newAge} in the year ${year}`;
  } else if (newAge< 0) { 
    return `The year ${year} was ${Math.abs(newAge)} years before you were born`;
  } else if (newAge< age) {
    return `You were ${newAge} in the year ${year}`;
  }
};

console.log(howOld(26,1990));
//print >> The year 1990 was 4 years before you were born