Question

我不知道为什么javascript不起作用。不显示警报消息。这是一个简单的html文件，用于验证用于将书籍添加到数据库的表单。在点击提交按钮时，页面会将自己定向到以下链接，而不会延迟警报窗口。请帮助我。

 <!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN"
 "http://www.w3.org/TR/html4/loose.dtd">

 <html xmlns="http://www.w3.org/1999/xhtml">
<head>
   <title>Add Book</title>
   <link rel="stylesheet" type="text/css" media="screen" href="css/default.css" />
</head>
<body id="index_page">
 <div id="wrapper">
    <div id="header">
        <h1 align="left">Library</h1>
    </div> 
    <ul id="navigation">
        <li id="index"><a href="http://localhost/UID/FAQ.php">FAQ</a></li>
    </ul>
    <div id="content">
    <div id="main_content">
    <h2>Add book</h2>
  <h4>Enter details of the book</h4>
  <FORM action="add_book_action.php" method="post" >
   <TABLE WIDTH="50%" >

    <TR>
      <TH width="50%">Book ID:</TH>
      <TD width="50%"><INPUT TYPE="text" name="id" id="book_id"></TD>
  </tr>
  <TR>
      <TH width="50%">Book Name:</TH>
      <TD width="50%"><INPUT TYPE="text" name="name" id="book_name"></TD>
  </tr>
  <TR>
      <TH width="50%">Book Author:</TH>
      <TD width="50%"><INPUT TYPE="text" NAME="author" id="book_author"></TD>
  </tr>  
  <TR>
      <TH width="50%">Year of Publication:</TH>
      <TD width="50%"><INPUT TYPE="text" NAME="pub" id="book_year"></TD>
  </tr>
  <TR>
      <TH></TH>
      <TD width="50%"><INPUT TYPE="submit" Value="Submit" onclick="return   validate_fun()"></TD>
  </tr>
  </TABLE>
  </FORM>

  </div>
     <p id="footer"><a href="http://localhost/UID/UID.php">@AntonyAjay,2012</a></p>
    </div>


 <script language="javascript">
 function validate_fun()
 {
  var x=document.getElementById("book_id").value;
   if(x==""||isNaN(x))
{
alert("Book Id should be numeric");
return false;   
}
  var x=document.getElementById("book_name").value;
 var regex = /^[a-zA-Z ]*$/;
 if(!(regex.test(x)))
{
alert("Book Name should be only characters and spaces");
return false;   
}
  var x=document.getElementById("book_author").value;
  var regex = /^[a-zA-Z ]*$/;
  if(!(regex.test(x)))
{
alert("Author Name should be only characters and spaces");
return false;   
}
  }

  var x = document.getElementById("book_year").value;

  var regExp = /^([1][6-9][0-9][0-9]|[2][0][01][0-9]\/|-([1-9]|[1][0-9]|[2][0-9]|[3][01])\/|-([1-9]|[1][012])$/;

   if(!(regExp.test(x)))
   {
alert("Enter date in yyyy-mm-dd format");
return false;
   }
  }
 </script>
  </body> 
 </html>

Answer 1

除了额外的}之外，您的代码缺少关闭<div #wrapper>，此RegExp也有一个无对齐的括号：

var regExp = /^([1][6-9][0-9][0-9]|[2][0][01][0-9]\/|-([1-9]|[1][0-9]|[2][0-9]|[3][01])\/|-([1-9]|[1][012])$/;

使用浏览器的开发工具时，所有这些都可以在两秒内找到...

Answer 2

正如大家已经建议的那样，请使用任何现代浏览器中的开发者工具，它将能够告诉你更多。如果您仍在努力，修改下面的代码，但这些都是愚蠢的错误，所以请确保您有一个IDE可以进行缩进并检查丢失或额外的大括号。

 <!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN"
 "http://www.w3.org/TR/html4/loose.dtd">

 <html xmlns="http://www.w3.org/1999/xhtml">
<head>
   <title>Add Book</title>
   <link rel="stylesheet" type="text/css" media="screen" href="css/default.css" />
</head>
<body id="index_page">
 <div id="wrapper">
    <div id="header">
        <h1 align="left">Library</h1>
    </div> 
    <ul id="navigation">
        <li id="index"><a href="http://localhost/UID/FAQ.php">FAQ</a></li>
    </ul>
    <div id="content">
    <div id="main_content">
    <h2>Add book</h2>
  <h4>Enter details of the book</h4>
  <FORM action="add_book_action.php" method="post" >
   <TABLE WIDTH="50%" >

    <TR>
      <TH width="50%">Book ID:</TH>
      <TD width="50%"><INPUT TYPE="text" name="id" id="book_id"></TD>
  </tr>
  <TR>
      <TH width="50%">Book Name:</TH>
      <TD width="50%"><INPUT TYPE="text" name="name" id="book_name"></TD>
  </tr>
  <TR>
      <TH width="50%">Book Author:</TH>
      <TD width="50%"><INPUT TYPE="text" NAME="author" id="book_author"></TD>
  </tr>  
  <TR>
      <TH width="50%">Year of Publication:</TH>
      <TD width="50%"><INPUT TYPE="text" NAME="pub" id="book_year"></TD>
  </tr>
  <TR>
      <TH></TH>
      <TD width="50%"><INPUT TYPE="submit" Value="Submit" onclick="return   validate_fun()"></TD>
  </tr>
  </TABLE>
  </FORM>

  </div>
     <p id="footer"><a href="http://localhost/UID/UID.php">@AntonyAjay,2012</a></p>
    </div>


 <script language="javascript">
 function validate_fun()
 {
    var x=document.getElementById("book_id").value;
    if(x==""||isNaN(x))
    {
        alert("Book Id should be numeric");
        return false;   
    }
    var x=document.getElementById("book_name").value;
    var regex = /^[a-zA-Z ]*$/;
    if(!(regex.test(x)))
    {
        alert("Book Name should be only characters and spaces");
        return false;   
    }
    var x=document.getElementById("book_author").value;
    var regex = /^[a-zA-Z ]*$/;
    if(!(regex.test(x)))
    {
        alert("Author Name should be only characters and spaces");
        return false;   
    }
    var x = document.getElementById("book_year").value;
    var regExp = /^([1][6-9][0-9][0-9]|[2][0][01][0-9]\/|-([1-9]|[1][0-9]|[2][0-9]|[3][01])\/|-([1-9]|[1][012])$/;

    if(!(regExp.test(x)))
    {
        alert("Enter date in yyyy-mm-dd format");
        return false;
    }
  }
 </script>
  </body> 
 </html>

javascript中的警报无法按预期工作

2 个答案: