Question

我仍然无法为此获得正确的流量。我知道这很简单，我认为我的代码是正确的，但即使输入框为空，当我点击购买按钮时仍会显示警告消息。我想要的是，如果输入框为空，但如果输入框已填满，则不显示任何警告消息; s是单击按钮时警报消息显示的唯一时间。这是我的代码：

 <?php
require_once('auth.php');
 ?>
 <!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Transitional//EN"  "http://www.w3.org/TR/xhtml1/DTD/xhtml1-transitional.dtd">
 <html xmlns="http://www.w3.org/1999/xhtml">
 <head>
 <meta http-equiv="Content-Type" content="text/html; charset=iso-8859-1" />
 <title>Athan Motorcycle</title>
 <style type="text/css">
 <!--
 .style1 {
color: #000000;
font-weight: bold;
font-size: 24px;
  }
  -->
  </style>
  <!--<script type="text/javascript">
  function validateForm()
  {
  var a=document.forms["abc"]["qty"].value;
  if ((a==null || a==""))
  {
  alert("Please specify the quantity.");
   return false;
  }
  }
  </script>-->

  </head>
  <body>
  <form action="saveorder.php" name="abc" method="post">
  <input name="id" type="hidden" value="<?php echo $_SESSION['SESS_MEMBER_ID']; ?>" />
  <input name="transcode" type="hidden" value="<?php echo $_SESSION['SESS_FIRST_NAME'];   ?>" />
  <table width="400" border="0" cellpadding="0" cellspacing="0">
  <?php
              if (isset($_GET['id']))
        {


        include('config.php');

        $id=$_GET['id'];
        $result = mysql_query("SELECT * FROM athan_products WHERE     product_id = $id and status='available'");
        $row3 = mysql_fetch_array($result);
  echo '<tr>';
  echo '<td width="80"><img alt="Motor" src="images/motor/'.$row3['product_photo'].'"      /></td>';
  echo '<td width="200"><span class="style1">'.'</span></td>';
echo '<td width="120"></span></td>';
  echo '</tr>';
  echo '<tr>';
  echo '<td width="80"><input name="name" type="text" value="'.$row3['partsname'].'"      readonly/><input name="ingre" type="hidden" value="'.$row3['product_ingredients'].'"/>      <input name="ids" type="hidden" value="'.$row3['id'].'"/></td>';
    echo '<td width="120"></span></td>';
  echo '</tr>';
  }
        ?>
  </table>
  <br />
  <label style="color:#000000;">Qty:
  <input type="number" min="1" id="qty" name="qty" required = "required" />


  </label>
  <br />
  <table width="400" border="0" cellpadding="0" cellspacing="0" style="color:#000000;"> 
  <tr>

   <!--<td width="179">Size</td>-->
  <td width="128">Price</td>
<td width="179">Description</td>
   <td width="93">Selection</td>
   </tr>
   <?php
              if (isset($_GET['id']))
        {


        include('config.php');

        $id=$_GET['id'];
        $result = mysql_query("SELECT * FROM athan_products WHERE     product_id = $id");
        while($row3 = mysql_fetch_array($result))
        {
        $resultq = mysql_query("SELECT * FROM inventory WHERE product_id     LIKE '%".$id."%'");
        //$resultq = mysql_query("SELECT * FROM inventory WHERE product_id LIKE =$id");
        while($rows = mysql_fetch_array($resultq))
  { 
  $qwerty=$rows['qtyleft'];
  }     
  if ($qwerty !=0){         
  echo '<tr>';
   //echo '<td>'.$row3['product_size_name'].'</td>';
   echo '<td>'.$row3['price'].'</td>';
echo '<td>'.$row3['description'].'</td>';
    echo '<td>'.'<input name="but" type="image" value="'.$row3['id'].'"      src="images/button.png"  onclick="return myFunction()" />'.'</td>';



   echo '</tr>';
   }
   else
   {
    echo '"This Item is not Available"';
    //echo '<td>'.'<h1>'.'"not available"'.'</h1>'.'</td>';
    }

        }

        }
        ?>


  </table>
  </form>
  <script type="text/javascript">
        function myFunction()
        {
        var a=document.forms["abc"]["qty"].value;
         if (a!=null || a!= ""){
        alert("Item has been successfully added to your Cart");
        }
        }
        </script>
  </body>
  </html>

Answer 1

你的OR应该是AND：

if(a!=null && a!= "")

由于a不等于null，因此条件为真

Answer 2

不应检查null还是empty，而应检查a.length是否为0

if(a.length !== 0){
 // do stuff
}

表单中的警报消息

2 个答案: