JSFiddle - React, Tailwind, and code Playground

HTML

<form action="#">
    Num1:<input name="num1"><br>
    <input type='radio'  name='express' value='+' />+
    <input type='radio'  name='express' value='-' />-
    <input type='radio'  name='express' value='*' />*
    <input type='radio'  name='express' value='/' />/
    <br>
    Num2:<input name="num2" /> 
        Result<input id="result" name="result" value="0">
</form>

JavaScript

function CalculateVals(Obj)
{
    var UseOpr	=	$("input[name='express']:checked").val();
    var Result	=	0;
    var n1		=	$("input[name='num1']").val();
    var n2		=	$("input[name='num2']").val();
    var Num1	=	(!isNaN(n1))? n1:0;
    var Num2	=	(!isNaN(n2))? n2:0;
    
    switch(UseOpr) {
    	case('+'):
            Result = +Num1 + +Num2;
            break;
    	case('-'):
            Result = +Num1 - +Num2;
            break;
    	case('*'):
            Result = +Num1 * +Num2;
            break;
    	case('/'):
            Result = +Num1 / +Num2;
    }
    
  $("#result").val(Result);
}

$("form").change(function() {
	CalculateVals($(this));
});