Drop rate calculator

Num1: 0

Num2: 0

Operation: +

Calculate

Result: 0

<script> document.addEventListener("DOMContentLoaded", function() {

 const btn = document.getElementById("calcButton");
 btn.addEventListener("click", function() {
   const a = parseFloat(document.getElementById("num1").textContent);
   const b = parseFloat(document.getElementById("num2").textContent);
   const op = document.getElementById("op").textContent;
   let result;

   if (isNaN(a) || isNaN(b)) {
     result = "Enter valid numbers";
   } else {
     switch(op) {
       case "+": result = a + b; break;
       case "-": result = a - b; break;
       case "*": result = a * b; break;
       case "/": result = b !== 0 ? a / b : "∞"; break;
       default: result = "Error";
     }
   }

   document.getElementById("result").textContent = result;
 });

}); </script>