렛츠기릿 자바스크립트 7 (계산기) -self(연달아 계산)

계산기 - 연달아계산 버전1

let numOne ='';
let operator='';
let numTwo='';
const $operator = document.querySelector('#operator');
// console.log($operator)
const $result = document.querySelector('#result');
// console.log($result)
const onClickNumber = (event) =>{
    if(!operator){//연산자가 비어 있으면 
        numOne +=event.target.textContent
        $result.value+=event.target.textContent
        return
    }    
    //연산자가 있으면 
    if(!numTwo){
        $result.value ='';
    }
    numTwo +=event.target.textContent
    $result.value+=event.target.textContent
       
};

document.querySelector('#num-0').addEventListener('click', onClickNumber);
document.querySelector('#num-1').addEventListener('click', onClickNumber);
document.querySelector('#num-2').addEventListener('click', onClickNumber);
document.querySelector('#num-3').addEventListener('click', onClickNumber);
document.querySelector('#num-4').addEventListener('click', onClickNumber);
document.querySelector('#num-5').addEventListener('click', onClickNumber);
document.querySelector('#num-6').addEventListener('click', onClickNumber);
document.querySelector('#num-7').addEventListener('click', onClickNumber);
document.querySelector('#num-8').addEventListener('click', onClickNumber);
document.querySelector('#num-9').addEventListener('click', onClickNumber);

const onClickOperator = (op) => () =>{
    if(numOne){
        operator = op;
        $operator.value =op;
    } else {
        alert('숫자를 먼저 입력하세요');
    }
}
document.querySelector('#plus').addEventListener('click', onClickOperator('+'));
document.querySelector('#minus').addEventListener('click', onClickOperator('-'));
document.querySelector('#divide').addEventListener('click', onClickOperator('/'));
document.querySelector('#multiply').addEventListener('click', onClickOperator('*'));
document.querySelector('#calculate').addEventListener('click', ()=>{
    if(numTwo){
        if(operator==='+'){
            $result.value =parseInt(numOne) + parseInt(numTwo);
           
        }
        else if(operator ==='-'){
            $result.value =parseInt(numOne) - parseInt(numTwo);
           
        }
        
        else if(operator ==='/'){
            $result.value =parseInt(numOne) / parseInt(numTwo);
          
        } 
          
        else if(operator ==='*'){
            $result.value =parseInt(numOne) * parseInt(numTwo);
           
        } 
        $operator.value = ''; //연산자를 없앤다.
        numOne = $result.value //연산결과값이 numOne이 된다.
        operator='';
        numTwo ='';
          
    } else{
          alert('숫자를 먼저 입력하세요');
    }
});
document.querySelector('#clear').addEventListener('click', ()=>{
    numOne = '';
    operator ='';
    numTwo = '';
    $operator.value = '';
    $result.value = '';
});