javascript - 为什么这个 window.onload 没有触发我的函数？

Question

我有一个计算器脚本，每当单击或更改字段时，它都会计算表单。它工作得很好，但我也希望在页面加载时使用其默认值来计算表单。所以我添加了

window.onload=Calc(form) ;

在表单的末尾，但它不起作用并且不计算表单。我究竟做错了什么？这可能是一个显而易见的答案，只是对我来说并不明显。感谢您的帮助!

<script type="text/javascript">// <![CDATA[
//  Javascript Mortgage Calculator
function Calc(form) {
 var x, y, incm, intRate = 0;
  intRate = form.rate.value / 100 / 12;
  p = form.term.value * 12;
  form.down.value = form.price.value * form.pdown.value / 100;
  form.loan.value = form.price.value - form.down.value;
  x = form.loan.value * intRate * Math.pow(1 + intRate, p);
  y = Math.pow(1 + intRate, p) - 1;
  form.pni.value = parseInt(x / y);
  form.taxes.value = parseInt(form.price.value * form.taxrate.value / 1200);
  form.ins.value = parseInt(form.price.value * form.insrate.value / 1200);
                form.pmirate.value = 0;
  if (form.pdown.value < 20) {
   form.pmirate.value = .5;
  }
  if (form.pdown.value < 10) {
   form.pmirate.value = .9;
  }
  form.pmi.value = parseInt(form.loan.value * form.pmirate.value / 1200);
  form.piti.value = parseInt(form.pni.value) + parseInt(form.taxes.value) + parseInt(form.ins.value) + parseInt(form.pmi.value);



 }
function Hnt(form,f) {
 var text = "No Hint available for this field!";
  if (form.pni.value == "") {
   Calc(form);
  }
  if (f == "price") {
   text = "Enter the purchase price of the home.";
  }
  if (f == "pdown") {
   text = "Enter the percent that you will put down, usually 5, 10, or 20%.";
  }
  if (f == "loan") {
   text = "This is the financed loan amount borrowed from the lender.";
  }
  if (f == "down") {
   text = "This is the down payment amount, not including closing costs.";
  }
  if (f == "rate") {
   text = "Enter the interest rate for the loan in percent.";
  }
  if (f == "term") {
   text = "Enter the term in years for the loan, usually 15 or 30.";
  }
  if (f == "pni") {
   text = "This is the total principal and interest portion of your monthly payment.";
  }
  if (f == "taxrate") {
   text = "This is the total percentage per year of state, county, and city taxes, as a percentage of the purchase price.";
  }
  if (f == "insrate") {
   text = "This is Homeowner' Insurance rate per year, as a percentage of the loan amount.";
  }
  if (f == "ins") {
   text = "This is the total Homeowners Insurance per month.";
  }
  if (f == "pmirate") {
   text = "Private Mortgage Insurance is required for loans over 80%. This is calculated as a percentage per year of the loan amount.";
  }
  if (f == "pmi") {
   text = "This is the Private Mortgage Insurance per month.";
  }
  if (f == "piti") {
   text = "This is the total monthly payment, PITI, Principal + Interest + Taxes + Insurance";
  }
  if (f == "inc") {
   text = "Enter your total combined annual gross income.";
  }
  if (f == "taxes") {
   text = "This is the total taxes per month.";
  }
  if (f == "debt") {
   text = "Enter your total monthly debt, car loans, credit cards, student loans, etc.";
  }
  if (f == "taxes") {
   text = "This is the total taxes per month.";
  }
  if (f == "fr") {
   text = "Ratio of PITI to your monthly income. Most lenders require 28% or less.";
  }
  if (f == "bk") {
   text = "Ratio of (PITI+debt) to your monthly income. Most lenders require 36% or less";
  }
  if (f == "qualtext") {
   text = "Do you qualify?, and if you don't, why not?";
  }
  if (f == "hint") {
   text = "This field displays hints for the field that currently has the cursor in it.";
  }

 }
// ]]></script>
<center><form></form></center><center>
<p></p>
<form id="Calculator">
<table cellspacing="0" bordercolordark="#999999" cellpadding="0" bordercolorlight="#CCCCCC" border="2" style="background-color: #fffdf6;">
<tbody>
<tr><th colspan="3">
<h3>Mortgage Calculator</h3>
<p>Click any field to calculate the payment information.</p>
</th></tr>
<tr>
<td>
<table valign="top">
<tbody>
<tr><th valign="top" align="center" colspan="2">Purchase Information</th></tr>
<tr>
<td align="right">Home Price $</td>
<td><input onfocus="Hnt(this.form,this.name)" onchange="Calc(this.form)" size="5" value="200000" name="price" type="text" /></td>
</tr>
<tr>
<td align="right">Down %<input onfocus="Hnt(this.form,this.name)" onchange="Calc(this.form)" size="1" value="10" name="pdown" type="text" />$</td>
<td><input onfocus="Hnt(this.form,this.name)" onchange="Calc(this.form)" size="5" name="down" type="text" /></td>
</tr>
<tr>
<td align="right">Loan Amount $</td>
<td><input onfocus="Hnt(this.form,this.name)" onchange="Calc(this.form)" size="5" name="loan" type="text" /></td>
</tr>
<tr>
<td align="right">Interest Rate %</td>
<td><input onfocus="Hnt(this.form,this.name)" onchange="Calc(this.form)" size="5" value="5" name="rate" type="text" /></td>
</tr>
<tr>
<td align="right">Term Years</td>
<td><input onfocus="Hnt(this.form,this.name)" onchange="Calc(this.form)" size="5" value="30" name="term" type="text" /></td>
</tr>
</tbody>
</table>
</td>
<td>
<table valign="top">
<tbody>
<tr><th valign="top" align="center" colspan="3">Payment Information</th></tr>
<tr>
<td align="right" colspan="2">Principal and Interest $</td>
<td><input onfocus="Hnt(this.form,this.name)" onchange="Calc(this.form)" size="5" name="pni" type="text" /></td>
</tr>
<tr>
<td style="visibility: hidden;" align="right">Prop Tax Rate %</td>
<td style="visibility: hidden;"><input onfocus="Hnt(this.form,this.name)" onchange="Calc(this.form)" size="4" value="0" name="taxrate" type="text" />= $</td>
<td style="visibility: hidden;"><input onfocus="Hnt(this.form,this.name)" onchange="Calc(this.form)" size="5" name="taxes" type="text" /></td>
</tr>
<tr>
<td align="right" style="visibility: hidden;">Insurance Rate %</td>
<td style="visibility: hidden;"><input onfocus="Hnt(this.form,this.name)" onchange="Calc(this.form)" size="4" value="0" name="insrate" type="text" />= $</td>
<td style="visibility: hidden;"><input onfocus="Hnt(this.form,this.name)" onchange="Calc(this.form)" size="5" name="ins" type="text" /></td>
</tr>
<tr>
<td align="right">PMI Rate %</td>
<td><input onfocus="Hnt(this.form,this.name)" onchange="Calc(this.form)" size="4" name="pmirate" type="text" />= $</td>
<td><input onfocus="Hnt(this.form,this.name)" onchange="Calc(this.form)" size="5" name="pmi" type="text" /></td>
</tr>
<tr>
<td align="right" colspan="2">Total Payment $</td>
<td><input onfocus="Hnt(this.form,this.name)" onchange="Calc(this.form)" size="5" name="piti" type="text" /></td>
</tr>
<tr></tr>
</tbody>
</table>
</td>
<td></td>
</tr>
</tbody>
</table>
</form></center>
<script type="text/javascript">// <![CDATA[
window.onload=Calc(form) ;
// ]]></script>

Answer 1

您注册的不是您的函数，而是该函数的返回值，该值是未定义。

替换

window.onload=Calc(form) ;

与

window.onload=function(){ // define a new function
   Calc(document.getElementById('Calculator')) // find the form and pass it as argument
};