This code is for Sales Tax calculation, base on a percent selection dropdown box.
If I enter the amount and click calculate, I get the NaN undefined error. I think that the issue is that the number totalAmount variable is interpreted as a string.
<!DOCTYPE html>
<html>
<head>
<h2>Sales Tax</h2>
</head>
<body>
<select id="ivu" name="ivu" class="drpdwni-content">
<option href="#7" value=7>7</option>
<option href="#11.5" value=11.5>11.5</option>
</select>
<p id="outrig" ></p>
<div class=subContainer>
<form action="/action_page.php">
<label for="subTotal">SubTotal</label>
<input type="number" step="0.01" min=0 id="sub" name="sub" class="calculate" placeholder="SubTotal...">
<input type="submit" value="Calculate" onclick="myFunction()">
</form>
</div>
<script type="text/javascript">
function myFunction() {
var subTotal = document.getElementById("sub").value
var per = document.getElementById("ivu").value
// I think that the issue maybe is the number variable totalAmount interpreted as string
var sub = subTotal
var ivu = per / 100
var totalIvu = ivu * sub
var totalAmount = totalIvu + sub
// To get totalAmount formated $#,###.##
var totalAmount = formatDollar(totalAmount)
document.getElementById("outrig").innerHTML = per + "%<br>" + sub + "<br>" + totalIvu + "<b>" + totalAmount + "</b>"
function formatDollar(num) {
var p = num.toFixed(2).split(".");
return "$" + p[0].split("").reverse().reduce(function(acc, num, i, orig) {
return num=="-" ? acc : num + (i && !(i % 3) ? "," : "") + acc;
}, "") + "." + p[1];
}
</script>
</body>
</html> ```