Question

所以在html体内我都有

<script type="text/javascript">
function validateMelco(form) {
    toReturn=true;
  if (form.melco.value.length==0) {
    alert("Please enter your Melco serial no");
    toReturn=false;
  }
  return toReturn;
}
</script>

和

<tr>
<td valign="top"><b>SongKong for Melco  (Melco discount)</b>
</td>
<td  valign="top">£40 ($50 USD)
</td>
<td  valign="top">
<form name="paypalpro" action="https://www.paypal.com/cgi-bin/webscr" onsubmit="return validateMelco()" method="post">
<input type="hidden" name="cmd" value="_s-xclick">
<input type="hidden" name="hosted_button_id" value="5UC5NAYZ6JZR8">
<input alt="PayPal" type="image" src="https://www.paypal.com/en_US/i/btn/btn_xpressCheckout.gif" border="0" name="submit">
<img alt="" border="0" src="https://www.paypalobjects.com/en_GB/i/scr/pixel.gif" width="1" height="1">
Melco Serial No:<input type="textfield" name="melco"/>
</form>
</td>
</tr>

然而，用户可以单击该按钮而不在输入字段中输入任何内容，不显示警报并且发布表单。为什么JavaScript验证没有开始？

Answer 1

更改行

<form name="paypalpro" action="https://www.paypal.com/cgi-bin/webscr" onsubmit="return validateMelco()" method="post">

到

<form name="paypalpro" action="https://www.paypal.com/cgi-bin/webscr" onsubmit="return validateMelco(this)" method="post">

Answer 2

您在没有参数的情况下调用该函数，但它需要一个标识该表单的参数。所以它什么都做不了。

Answer 3

<!DOCTYPE html>
<html>
<body>

<p>When you submit the form, a function is triggered which alerts some text.</p>

<tr>
<td valign="top"><b>SongKong for Melco  (Melco discount)</b>
</td>
<td  valign="top">£40 ($50 USD)
</td>
<td  valign="top">
<form name="paypalpro" action="https://www.paypal.com/cgi-bin/webscr" onsubmit="return validateMelco()" method="post">
<input type="hidden" name="cmd" value="_s-xclick">
<input type="hidden" name="hosted_button_id" value="5UC5NAYZ6JZR8">
<input alt="PayPal" type="image" src="https://www.paypal.com/en_US/i/btn/btn_xpressCheckout.gif" border="0" name="submit">
<img alt="" border="0" src="https://www.paypalobjects.com/en_GB/i/scr/pixel.gif" width="1" height="1">
Melco Serial No:<input type="textfield" name="melco"/>
</form>
</td>
</tr>

<script>
function validateMelco(form) {
    toReturn=true;

  if (document.forms["paypalpro"]["melco"].value == "") {
    alert("Please enter your Melco serial no");
    toReturn=false;
  }
  return toReturn;
}
</script>

</body>
</html>

表单对象尚未传递给函数“validateMelco（）”以访问表单元素。所以我使用javascript文档对象使用'document.forms [“paypalpro”] [“melco”]'来访问表单。

为什么在发布之前没有验证html输入字段

3 个答案: