app.js

//* =================================================
//*                     IOS CALCULATOR
//* =================================================
//? Ekranlar
const prevDisp = document.querySelector('.previous-display');
const currDisp = document.querySelector('.current-display');

//?Button container
const btnContainer = document.querySelector('.buttons-container');

//? ara degerler icin degisken tanimlamalari
let currOperand = '';
let previousOperand = '';
let operation = '';

let equalOrPercentPressed = false;

//? Butonlari tasiyan container icin event tanimlamasi
btnContainer.addEventListener('click', (e) => {
  //? Herhangi bir sayi(num) sayiya tiklanildi ise
  if (e.target.classList.contains('num')) {
    appendNumber(e.target.textContent);
    updateDisplay();
  }

  //? Herhangi bir operator butonuna (+,-,x,/) tiklanildi ise
  if (e.target.classList.contains('operator')) {
    chooseOperator(e.target.textContent);
    updateDisplay();
  }
  //? Esittir butonuna tiklanildi ise
  if (e.target.classList.contains('equal')) {
    calculate();
    updateDisplay();
    equalOrPercentPressed = true;
  }

  //? AC butonuna tiklanildi ise
  if (e.target.classList.contains('ac')) {
    previousOperand = '';
    currOperand = '';
    operation = '';
    updateDisplay();
  }

  //? PM butonuna tiklanildi ise
  if (e.target.classList.contains('pm')) {
    if (!currOperand) return;
    currOperand *= -1;
    updateDisplay();
  }

  //? Percent butonuna tiklanildi ise
  if (e.target.classList.contains('percent')) {
    if (!currOperand) return;
    currOperand = currOperand / 100;
    updateDisplay();
    equalOrPercentPressed = true;
  }
});

const appendNumber = (num) => {
  //? Eger onceden 0 girilmisse ve tekrardan 0 girilise geri don
  if (currOperand === '0' && num === '0') return;

  //? Eğer ilk olarak 0 girilmisse ve sonrasinda da . haricinde baska
  //? bir sayi girilmis ise sadece girilen yeni sayiyi degiskene aktar.
  //? Orn: 09 => 9 , 03 => 3 , 0.1 => 0.1
  if (currOperand === '0' && num !== '.') {
    currOperand = num;
    return;
  }

  //? Eğer şu anki sayi . ise ve önceki girilen sayi . iceriyorsa geri don
  if (num === '.' && currOperand.includes('.')) return;

  if (currOperand.length > 10) return;

  if (equalOrPercentPressed) {
    currOperand = num;
    equalOrPercentPressed = false;
    return;
  }
  //? Girilen sayilari birlestir.
  currOperand += num;
};

const updateDisplay = () => {
  if (currOperand.toString().length > 11) {
    currOperand = Number(currOperand).toExponential(3);
  }
  currDisp.textContent = currOperand;

  //! Eger bir sayiya basilmadan operator butonlarina basilirsa
  //! prevDisp'de operatoru gosterme
  if (operation && previousOperand) {
    prevDisp.textContent = `${previousOperand} ${operation}`;
  } else {
    prevDisp.textContent = '';
  }
};

const chooseOperator = (op) => {
  //? ilk sayi girisiinden sonraki islemleri gercekletir
  if (previousOperand) {
    calculate();
  }

  //? Degisken swapiing
  operation = op;
  previousOperand = currOperand;
  currOperand = '';
};

const calculate = () => {
  let calculation = 0;

  const prev = Number(previousOperand);
  const current = Number(currOperand);

  switch (operation) {
    case '+':
      calculation = prev + current;
      break;
    case '-':
      calculation = prev - current;
      break;
    case 'x':
      calculation = prev * current;
      break;
    case '÷':
      calculation = prev / current;
      break;
    default:
      return;
  }

  currOperand = calculation;

  //? Esittir butonuna tiklanildiginda ekranda gozukmemesi icin
  //? previousOperand ve operation'ı silmemiz gerekir
  previousOperand = '';
  operation = '';
};