[프로그래머스 문제풀이26]연습문제2016 자바스크립트

function solution(a, b) {
    var answer = '';
    const months=[];
    const days=["FRI","SAT","SUN","MON","TUE","WED","THU"]
    for(let i=0;i<7;i++){
         if(i==1){
            months.push(29);
              continue;
            } 
            if(i%2===0){
                months.push(31)
            }else{
                months.push(30);                
            }
             
    }
    for (let i=0;i<5;i++){
        if(i%2===0){
                months.push(31)
            }else{
                months.push(30);                
            }
    }
    
    let howManyDays=0;
    months.map((val,i)=>{
        if(i<a-1){
            howManyDays+=val;
        }
    })
    howManyDays+=b;
    const whatDay=(howManyDays%7-1);
    answer=days[whatDay===-1?6:whatDay]
    return answer;
}

무슨 요일인지 맞출 때 -1을 6으로 바꿔주어야 한다.