JavaScript- if문

if문(범위가 있을때 사용하면 편함)

        - if(조건식){
            조건식의 결과가 true일 때 실행할 문장;
            ...
        }


        - if~else문
            if(조건식){
            조건식의 결과가 true일 때 실행할 문장;
            ...
        }else{
            조건식의 결과가 false일 때 실행할 문장;
            ...
        }


        - if~else if~else
        if(조건식1){
            조건식1의 결과가 true일 때 실행할 문장;
            ...
        }else if(조건식2){
            조건식2의 결과가 true일 때 실행할 문장;
            ...
        }else if(조건식3){
            ....
            ....
        }else{
            모든 조건식의 결과가 false일때 실행할 문장;
            ...
        }