script.js

const calculatorDisplay = document.querySelector('h1');
const inputBtns = document.querySelectorAll('button');
const clearBtn = document.getElementById('clear-btn');

const calculate = {
    '/': (firstNumber, secondNumber) => firstNumber / secondNumber,
    '+': (firstNumber, secondNumber) => firstNumber + secondNumber,
    '*': (firstNumber, secondNumber) => firstNumber * secondNumber,
    '-': (firstNumber, secondNumber) => firstNumber - secondNumber,
    '=': (firstNumber, secondNumber) => secondNumber,
    };

let firstValue = 0;
let operatorValue = '';
let awaitingNextValue = false;

function sendNumberValue(number){
  if(awaitingNextValue) {
      calculatorDisplay.textContent = number;
      awaitingNextValue = false;
  } else {
    const displayValue = calculatorDisplay.textContent;
    calculatorDisplay.textContent = displayValue === '0' ? number : displayValue + number;
  }
}

function addDecimal() {
    if(awaitingNextValue) return;
    if(!calculatorDisplay.textContent.includes('.') ) {
        calculatorDisplay.textContent = `${calculatorDisplay.textContent}.`
    }
}



function useOperator(operator) {
  const currentValue = Number(calculatorDisplay.textContent);

   if(operatorValue && awaitingNextValue) {
       operatorValue = operator;
       return;
   };

  if(!firstValue || firstValue.length > 3 ) {
      firstValue = currentValue;
      calculatorDisplay.textContent = firstValue.toLocaleString();
      calculatorDisplay.textContent = currentValue.toLocaleString();
    } else {
       const calculation = calculate[operatorValue](firstValue, currentValue).toLocaleString();
       calculatorDisplay.textContent = calculation;
        firstValue = calculation;
    }
  awaitingNextValue = true;
  operatorValue = operator;
}

inputBtns.forEach((inputBtn) => {
    if(inputBtn.classList.length === 0) {
       inputBtn.addEventListener('click', () => sendNumberValue(inputBtn.value)); 
    } else if(inputBtn.classList.contains('operator')) {
        inputBtn.addEventListener('click', () => useOperator(inputBtn.value)); 
    } else if(inputBtn.classList.contains('decimal')) {
        inputBtn.addEventListener('click', () => addDecimal()); 
    }
    });

    function resetAll() {
         firstValue = 0;
         operatorValue = '';
         awaitingNextValue = false;

        calculatorDisplay.textContent = '0';
    }

    clearBtn.addEventListener('click', resetAll);