Create a simple calculator with buttons and input fields

HTML

<div class="first">計數器：
  <button  class="sub"  onclick="Subtraction()">-</button>

  <button  class="add"  onclick="Addition()">+</button>
</div>      

<div class="second">簡單計算機

  <input type="text" class="num1"/>
  <input type="text" class="num2"/>
  <button  onclick="caall()">加/減/乘/除</button>
</div>

CSS

* {
  box-sizing: border-box;
}

.first {
  width: 300px;
}

.sub {
  width: 50px;
}

.add {
  width: 50px;
}

.second input {
  width: 60px;
}

JavaScript

let total1 = 0;
function Subtraction() {
  total1 --;
  alert(total1);
}

function Addition() {
  total1 ++ ;
  alert(total1);
}


let caall = () => {
  let num1 = parseInt(document.querySelector('.num1').value);

  let num2 = parseInt(document.querySelector('.num2').value);
  alert(num1 + num2);
  alert(num1 - num2);
  alert(num1 * num2);
  alert(num1 / num2);
}