Question

我有一个带JS函数的表单来验证没有空白字段，但它不起作用。

<head>
  <script language='javascript'>
      function verifyForm(){
        var msg='';
        if(document.getElementById('field1').value==''){msg+='Field 1  \n';}
        if(document.getElementById('field2').value==''){msg+='Field 2  \n';}
        if(msg!=''){
            alert('The following entries are empty:\n\n'+msg);
            return false
        }else{
            return true }
        }
  </script>
</head>

<body>
   <form name="frmRequest2" id="frmRequest2" action="<? echo $submitURL2; ?>" method="post" onsubmit='return verifyForm();'>
   Please answer all questions and enter "NONE" where appropriate.

  <table>
    <tbody>
      <tr>
        <th>List any items you already have</th>
        <th>List any items you need to get</th>
      </tr>
      <tr>
        <td><textarea name="field1" id="field1" rows="2" cols="39"> <? echo $field1; ?> </textarea></td>
        <td><textarea name="field2" id="field2" rows="2" cols="39"> <? echo $field2; ?> </textarea></td>
      </tr>

      <tr>
        <td colspan="4" align="center" valign="top" style="border-width: 0px 0px 0px 0px;"> <br />
        <input name="submit" value="Submit Data" type="submit"/> </td>
      </tr>      
    </tbody>
  </table>
  </form>
</body>

Answer 1

你的if子句后面有额外的大括号（}）。

编辑添加：以下代码按预期工作，并忽略字段中的任何前导/尾随空格：

<html>

<head>
  <script language='javascript'>
      function verifyForm(){
        var msg='';
        if(document.getElementById('field1').value.replace(/\s+$|^\s+/, '') == '') {msg+='Field 1  \n';}
        if(document.getElementById('field2').value.replace(/\s+$|^\s+/, '') == '') {msg+='Field 2  \n';}
        if(msg!=''){
            alert('The following entries are empty:\n\n'+msg);
            return false;
        }else{
            return true;
        }
      }
  </script>
</head>

<body>
   <form name="frmRequest2" id="frmRequest2" action="" method="post" onsubmit='return verifyForm();'>
   Please answer all questions and enter "NONE" where appropriate.

   <table>
      <tbody>
      <tr>
        <th>List any items you already have</th>
        <th>List any items you need to get</th>
      </tr>
      <tr>
        <td><textarea name="field1" id="field1" rows="2" cols="39"></textarea></td>
        <td><textarea name="field2" id="field2" rows="2" cols="39"></textarea></td>
      </tr>

      <tr>
        <td colspan="4" align="center" valign="top" style="border-width: 0px 0px 0px 0px;">
          <input name="submit" value="Submit Data" type="submit"/>
        </td>
      </tr>
    </tbody>
  </table>

 </form>
</body>

</html>

Answer 2

你错过了一个“＆gt;”在你的关闭“[/ head]”标签上，你没有关闭你的“[form]”标签。这可能会导致问题。

Answer 3

每个默认值的每一侧都有一个空格。 "" != " "

Answer 4

作为一般规则，我喜欢修剪输入空间。是否将if子句更改为

document.getElementById('field1').value == '' to
document.getElementById('field1').value.trim() == ''

有帮助吗？

另外，为了重申大卫建议的内容，您的原始代码看起来像

<textarea name="field1" id="field1" rows="2" cols="39"><? echo $field1; ?></textarea>

而不是

<textarea name="field1" id="field1" rows="2" cols="39"> <? echo $field1; ?> </textarea>

注意空格？

JS表单验证功能不起作用

4 个答案: