到底为什么这个Javascript程序无法运行？

Question

只是想用 JavaScript 制作一个简单的客户端抵押计算器。当我尝试运行它时，什么也没有发生。我认为它非常简单，但我就是无法弄清楚。有任何想法吗？我感谢你的帮助。

<html>
<head>
<title> Mortgage Calculator </title>

<script type = "text/javascript">
<!--
document.getElementById("mortgageCalc").calculateMortgage.onclick = CalcMortgage ();

function CalcMortgage ()
{
 var elt = document.getElementById("mortgageCalc");
 var P = elt.principal.value;
 var time = elt.interest.value;
 var n = elt.term.value;
 var isdigit = /^[-]?[0-9]+[\.]?[0-9]+$;
 
 if (isdigit.test(P) && isdigit.test(time) && isdigit.test(n))
 {
    var r = (time/100)/12;
    n = Math.round(n);
    
    var R = P*r/(1-(1/(Math.pow((1+r),n))));
    R = R.toFixed(2);
    
    var totalPayment = R*Number(n);
    totalPayment = totalPayment.toFixed(2);
    
    var totalInterest = totalPayment - P;
    totalInterest = totalInterest.toFixed(2);

    elt.monthlyPayment.value = R;
    elt.totalPayment.value = totalPayment;
    elt.totalInterest.value = totalInterest;
 }
 else
{
alert("Do not use non-numeric or negative numbers.");
}
}

// -->
</script>

</body>
</html>

</head>

<body>
<h3> Mortgage Calculator </h3>

<form id = "mortgageCalc" action = "" method = "post" >
<table border = "0">

<tr>
<td> Principal Amount: </td>
<td>
<input type = "text" name = "principal" size = "15" />
</td>
</tr>

<tr>
<td> Annual Interest Rate (%): </td>
<td>
<input type = "text" name = "interest" size = "15" />
</td>
</tr>

<tr>
<td> Loan Term (months): </td>
<td>
<input type = "text" name = "term" size = "15" />
</td>
</tr>

<tr>
<td>
<input type = "button" name = "calculateMortgage" value = "Calculate" />
</td>

<td>
<input type = "reset" value = "Clear" />
</td>
</tr>

<tr>
<td> Monthly Payments: </td>
<td>
<input type = "text" name = "monthlyPayment" value = "" size = "15" />
</td>
</tr>

<tr>
<td> Sum Total Payments: </td>
<td>
<input type = "text" name = "totalPayment" value = "" size = "15" />
</td>
</tr>

<tr>
<td> Total Interest Paid: </td>
<td>
<input type = "text" name = "totalInterest" value = "" size = "15" />
</td>
</tr>

</table>

</form>

Answer 1

您的正则表达式格式错误；缺少一个

。并且您在所有内容的中间（而不是末尾）都有结束 html 标签。然后，您调用 CalcMortage 并将结果附加为单击处理程序，而不是方法本身（因为

()

中的结束

onclick = CalcMortgage();

）。并且你在正则表达式中强制使用多个数字（就像我不能用“5”表示百分比）。

除此之外都还好。

Answer 2

您将返回值（即

undefined

）分配给此处的

onclick

处理程序：

document.getElementById("mortgageCalc").calculateMortgage.onclick = CalcMortgage ();

尝试删除“调用此函数”括号：

document.getElementById("mortgageCalc").calculateMortgage.onclick = CalcMortgage;

Answer 3

看起来你在定义它之前就已经对

CalcMortgage

进行了函数调用：

document.getElementById("mortgageCalc").calculateMortgage.onclick = CalcMortgage ();

考虑将其放在 CalcMortgage 定义之后：

document.getElementById("mortgageCalc").calculateMortgage.onclick = CalcMortgage;

到底为什么这个Javascript程序无法运行？

问题描述投票：0回答：3

3个回答

最新问题

到底为什么这个Javascript程序无法运行？

问题描述 投票：0回答：3

3个回答

最新问题

问题描述投票：0回答：3