JS表单验证不起作用

Question

我有一个表单，我有JS表单验证。但验证过程不起作用。插入过程中工作正常。

下面是将数据插入到MySQL的数据库 -

<?php 
session_start(); 
include("includes/connection.php"); 
include("header.php"); 
include("includes/adminmenu.php"); 
if(isset($_SESSION['username'])) 
     { 
     //echo $_SESSION['username']; 
     ?> 
     <!--Javasript Validation File Import --> 
<script type="text/javascript" src="js/qcheck.js"></script> 
<script type="text/javascript" language="JavaScript"> 

function HidePart(d) { document.getElementById(d).style.display = "none"; } 
function ShowPart(d) { document.getElementById(d).style.display = "block"; } 
function CheckboxChecked(b,d) 
{ 
    if(b) { ShowPart(d); } 
    else { HidePart(d); } 
} 
</script> 
    <br /> 
    <div class="userstat"> 

     <div style="background-color:#666666; text-align:center; font-weight:bold; color:#FFFFFF; font-size:24px;"><span>Insert A new Question</span></div> 
     <br /> 
     <div class="statdata"> 
      <form action="includes/insertq.php" method="POST" name="qform" onSubmit="return valide()"> 
        <div style="text-align:center;"> 
       <select name="subject" size="0"> 
       <option selected="0" value="">Select Subject</option> 
       <option value="bangla">Bangla</option> 
       <option value="english">English</option> 
       <option value="physics">Physics</option> 
       <option value="chemistry">Chemistry</option> 
       <option value="math">Mathematics</option> 
       <option value="biology">Biology</option> 
       <option value="gk">General knowledge</option> 
       </select> 
        </div> 
       <br /><br /> 
       <label for="question">Write Down the Question below</label> 
       <textarea name="question" rows="3" cols="40"></textarea><br /><br /> 
       <label for="ans">Options</label><br /><br /> 
       <label for="option1">a.</label> 
       <input type="text" name="option1" size="40" /><br /> 
       <label for="option2">b.</label> 
       <input type="text" name="option2" size="40" /><br /> 
       <label for="option3">c.</label> 
       <input type="text" name="option3" size="40" /><br /> 
       <label for="option4">d.</label> 
       <input type="text" name="option4" size="40" /><br /><br /> 
       <label for="correct">Correct.</label><br />&nbsp;&nbsp;&nbsp; 
       <input type="text" name="correct" size="40" /><br /><br /><br /> 
       <div style="text-align:center;"> 
       <input type="submit" name="submit" value="Submit Question" /> 
       </div> 
       <br /> 
       <br /> 
      </form> 
     </div> 
     </div> 

    </body> 
     <?php 
     } 



    else 
     { 
     header("location: admin.php"); 
     } 
?> 

<?php 
include("includes/footer.php"); 
?> 

和JavaScript文件的形式是

function valide() 
{ 
var subject=document.forms["qform"]["subject"].value; 
var question=document.forms["qform"]["question"].value; 
var option1=document.forms["qform"]["option1"].value; 
var option2=document.forms["qform"]["option2"].value; 
var option3=document.forms["qform"]["option3"].value; 
var option4=document.forms["qform"]["option4"].value; 
var correct=document.forms["qform"]["correct"].value; 

if(subject == null || Subject == "Select Subject") 
    { 
     alert("Select subject Type"); 
     return false; 

     } 
    else if(question==null || question=="" || question.length<5) 
     { 
      alert("Insert Valid question"); 
      return false; 
      } 
    else if(option1==null || option1=="") 
     { 
      alert("Insert Option 1."); 
      return false; 
      } 
    else if(option2==null || option2=="") 
     { 
      alert("Insert Option 2."); 
      return false; 
      } 
    else if(option3==null || option3=="") 
     { 
      alert("Insert option 3."); 
      return false; 
      } 
    else if(option4==null || option4=="") 
     { 
      alert("Insert option 4."); 
      return false; 
      } 
    else if(correct==null || correct=="") 
     { 
      alert("Insert correct option."); 
      return false; 
      }         





} 

Answer 1

情况下，重要的

if(subject == null || Subject == "Select Subject") 
        ^

主题！==主题

也值不会为空。你应该检查长度为零。