我正在做fv计算器。但是，我不知道为什么我的JavaScript代码在点击计算按钮后没有显示未来值的答案。
我该如何解决这个问题？
如果有人能为我提供帮助，我将不胜感激，谢谢。
下面是我的HTML和JavaScript代码。
<html>
<head>
<title>401K Future Value Calculator</title>
<script type="text/javascript" src="mpg.js"></script>
</head>
<body>
<h2>401K Future Value Calculator</h2>
<form id="calculationForm" >
<label for="periodicPayment">Yearly Investment($): </label>
<select id="yearlyInvest" name="Investment”">
<option value="1000: ">1000</option>
<option value="2000: ">2000</option>
<option value="3000: ">3000</option>
<option value="4000: ">4000</option>
<option value="5000: ">5000</option>
<option value="6000: ">6000</option>
<option value="7000: ">7000</option>
<option value="8000: ">8000</option>
<option value="9000: ">9000</option>
<option value="10000: ">10000</option>
</select><br><br>
<label for="annunalInterest">Annual Interest Rate(%) </label>
<input type="text" id="annunalInterestRate"><br><br>
<label for="years">Number of Years(#) </label>
<input type="text" id="numOfYears"><br><br>
<label for="future">Future Value($) </label>
<p id="futureValue">
</p>
<input type="button" id="calculate" value="Calculate">
<input type="button" onclick="clearButton()" id="clear" value="Clear">
</form>
</body>
</html>
function processForm() {
var r, n, p;
r = parseFloat(document.getElementById("annunalInterestRate").value);
n = parseInt(document.getElementById("numOfYears").value);
p = document.getElementById("yearlyInvest").value;
if (isNaN(r)) {
alert("Pleas enter a valid number.");
} else if (isNaN(n)) {
alert("Pleas enter a valid number.");
} else {
var fv = P * ((Math.pow((1 + r), n) - 1) / r);
}
document.getElementById("calculate").value;
document.getElementById("futureValue").innerHTML = fv.toFixed(2);
};
window.onload = function() {
document.getElementById("calculate").onclick = processForm;
};
function clearButton() {
document.getElementById("calculationForm").reset();
}
在<select>中写入<option>节点的方式在value=参数中包含不必要的:。这导致p计算为NaN。相反，重写为：
<select id="yearlyInvest" name="Investment”">
<option value="1000">1000</option>
<option value="2000">2000</option>
...
</select>