Php 如何使用javascript更改隐藏类型输入字段的值

我想做的是，每次用户单击Add按钮并调用addRow函数时，我还将调用row_计数器函数，以将隐藏输入类型字段的值设置为已创建的动态行数。因此，如果我动态创建了3行，那么隐藏的输入类型字段必须是3。我是javascript新手，请耐心等待

<?php 
// Parse the form data and add inventory item to the system
if (isset($_POST['product_name'])) {

    $product_name = mysql_real_escape_string($_POST['product_name']);
    $price = mysql_real_escape_string($_POST['counter']);
    $details = mysql_real_escape_string($_POST['details']); 
    $category = mysql_real_escape_string($_POST['category_choice']);
    $condition= mysql_real_escape_string($_POST['condition']);;
    $supplier_choice= mysql_real_escape_string($_POST['supplier_choice']);;

    // See if that product name is an identical match to another product in the system
    $sql = mysql_query("SELECT id FROM products WHERE product_name='$product_name' LIMIT 1");
    $productMatch = mysql_num_rows($sql); // count the output amount
    if ($productMatch > 0) {
        echo 'Sorry you tried to place a duplicate "Product Name" into the system, <a href="inventory_list.php">click here</a>';
        exit();
    }
    // Add this product into the database now
    $sql = mysql_query("INSERT INTO products (product_name, price, details, category, active, supplier, date_added) 
        VALUES('$product_name','$price','$details','$category','$condition','$supplier_choice',now())") or die (mysql_error());


     $pid = mysql_insert_id();
    // Place image in the folder 
    $newname = "$pid.jpg";
    move_uploaded_file( $_FILES['my_photo']['tmp_name'], "../inventory_images/$newname");
    //ean den yperxan oi 2 epomenes grammes ean ekana refresh tha prospathouse na perasei to idio proion ksana!!
    header("location: inventory_list.php"); 
    exit();

}

---

这应该适合您：

 document.getElementById("counter").value = 3;

---

这应该适合您：

 document.getElementById("counter").value = 3;

---

我这样做了，并尝试将counter的值插入我的sql，但在表的字段区域中，我得到一个空字段，这是代码的其余部分。您可以使用inventory\u list.php中的var\u dump$\u POST结果更新您的原始问题吗？我这样做了，并尝试将counter的值插入我的sql，但在表i得到一个空字段这里是代码的其余部分。您可以使用inventory\u list.php中的var\u dump$\u POST结果更新原始问题吗？我对您的问题进行了回滚。请不要再删除它了。我对你的问题做了回滚。请不要再删除它。

<div align="center" id="mainWrapper"> 

  <?php include_once("template_header.php");?>

  <div id="pageContent">

        <div align="left" style="margin-left:24px">
            <h2>Inventory List</h2>
            <?php echo $productList ?>
        </div>

  </div>

  <div>

        <form action="inventory_list.php" enctype="multipart/form-data" name="my_Form" id="my_Form" method="post">

        <a name="add_New_Product_Form" id="add_New_Product_Form">

            <h2>Add New Product Form</h2>

        </a>

        <table width="80%" border="0" cellspacing="0" cellpadding="6" id="dataTable">

            <tr>

                <td>Όνομα</td>
                <td>

                    <label>

                        <input name="product_name" type="text" id="product_name" size="80" />


                    </label>

                </td>

            </tr>

            <tr>

                <td>Κατάσταση</td>
                <td>

                    <label>

                        <input type="radio" name="condition" value="1"> Ενεργό</input>
                        <input type="radio" name="condition" value="0"> Ανενεργό</input>

                    </label>

                </td>

            </tr>


            <tr>

                <td>Τιμή</td>
                <td>

                    <label>

                        <input name="price" type="text" id="price" size="20" />

                    </label>

                </td>

            </tr>

            <tr>

                <td>Προμηθευτές</td>
                <td>

                    <?php echo $suppliers_list; ?>

                </td>

            </tr>

            <tr>

                <td>Κατηγορία</td>
                <td>

                    <?php echo $category_list; ?>

                </td>

            </tr>

            <tr>

                <td>Περιγραφή</td>
                <td>

                    <label>

                        <textarea name="details" id="details" cols="64" rows="5"></textarea>

                    </label>

                </td>

            </tr>

            <tr>

                <td>Τεχνικά Χαρακτηριστικά</td>
                <td>

                    <input type="text" name="information_0" id="information_0" size="84"/>

                </td>

            </tr>

            <tr>

                <td></td>
                <td>

                    <input type="hidden" name="counter" id="counter"/>
                    <INPUT type="button" value="Προσθήκη" onClick="addRow('dataTable','counter')"/>
                    <INPUT type="button" value="Αφαίρεση" onClick="deleteRow('dataTable')"/>

                </td>

            </tr>

            <tr>

                <td>Φωτογραφία</td>
                <td>

                    <label>

                        <input type="file" name="my_photo" id="my_photo"/>

                    </label>

                </td>

            </tr>

            <tr>

                <td>&nbsp;</td>
                <td>

                    <label>

                        <input type="submit" name="button" id="button" value="Αποθήκευση" />

                    </label>

                </td>

            </tr>

        </table>

        </form>



  </div>

   <br /><br />

  <?php include_once("../template_footer.php");?>

</div>

enter code here

 document.getElementById("counter").value = 3;