script1.js

const calculatorScreen = document.querySelector(".calculator-screen")
const updateScreen = (number) => {
    calculatorScreen.value = number
}
let prevInput = '0'
let calculationOperator = ''
let currentInput = '0'

const numbers = document.querySelectorAll(".number")
const inputNumber = (number) => {
    if(currentInput === '0'){
        currentInput = number
    }else{
    currentInput += number;
    }
}
numbers.forEach((number)=>{
    number.addEventListener("click", (event) =>{
        inputNumber(event.target.value)
        updateScreen(currentInput)
    })
})
const operators = document.querySelectorAll(".operator")
const inputOperator = (operator) =>{
    prevInput = currentInput
    calculationOperator = operator
    currentInput = '0'
}
operators.forEach((operator) =>{
    operator.addEventListener("click", (event)=>{
        inputOperator(event.target.value)
    })
})

const equalSign = document.querySelector(".equal-sign")
equalSign.addEventListener("click" , ()=> {
    calculate()
    updateScreen(currentInput)
})

const calculate = () => {
    let result = 0
    switch(calculationOperator) {
        case '+' :
            result = parseInt(prevInput) + parseInt(currentInput)
            break
        case '-' :
            result = parseInt(prevInput) - parseInt(currentInput)
            break
         case '*' :
            result = parseInt(prevInput) * parseInt(currentInput)
            break
         case '/' :
            result = parseInt(prevInput) / parseInt(currentInput)
            break
        default: 
            return
    }
    currentInput = result.toString()
    calculationOperator = ''
}


const clearBtn = document.querySelector(".all-clear")
const clearAll=() =>{
    prevInput = '0'
    calculationOperator = ''
    currentInput = '0'
}

clearBtn.addEventListener("click", () =>{
    clearAll()
    updateScreen(currentInput)
})