PHP變量值未顯示在JS警報中

Question

在以下代碼中，我生成了一個php表單，該表單接受了用戶正在處理的arp網絡攻擊的值。 但是，我試圖顯示在JavaScript警報中發送的“ $ loops”數據包的數量，當我運行代碼時，警報中未顯示數據包的數量，而且我不知道出了什么問題，所以如果有人可以通過我的代碼，我會非常感激。

<form method ='post' action ="<?php echo $_SERVER['PHP_SELF'];?>">

<?php $loops = "";?>

<b> <p>Number of packets to be sent:</p>
<input type="text" name="loops" value="<?php echo $loops;?>">
<br><br></b>

<?php
$php_var = $loops;?>


<p style="text-align: center;">
<button onclick="myFunction()">Submit</button></p><br>  
<script>
    function myFunction() {
            var js_var = "The number of packets sent is: <?php echo $php_var; ?>";
                    alert(js_var);
                        }
</script>
</font>
</form>


<?php
if($_SERVER["REQUEST_METHOD"]== "POST"){
if(isset($_POST["loops"])){
    $loops=$_REQUEST['loops'];
}
?>

Answer 1

您在此處將$php_var分配$php_var空白。

<?php $loops = "";?>

<?php $php_var = $loops;?>

因此，它沒有顯示任何價值。

我認為您需要在文本框中輸入用戶輸入的值。

<input type="text" name="loops" value="<?php echo $loops;?>" id="loops"> // Observe the added `id` attribute.

您可以這樣做：

<script>
function myFunction() {
  //var js_var = "The number of packets sent is: <?php echo $php_var; ?>";
  var val = document.getElementById('loops').value;
  var js_var = "The number of packets sent is: " + val;
  alert(js_var);
}
</script>

Answer 2

嘗試像

<?php $loops = "123";?>
    function myFunction() {
      var js_var = "The number of packets sent is: <?php echo $php_var; ?> ";
      alert(js_var);
    }

Answer 3

試試這個代碼

 <form method ='post' action ="<?php echo $_SERVER['PHP_SELF'];?>">

          $loops = isset($_POST["loops"])?$_POST["loops"]:"";

         <b> <p>Number of packets to be sent:</p>
        <input type="text" name="loops" value="<?php echo $loops;?>">
        <br><br></b>

       <?php
       $php_var = $loops;?>


       <p style="text-align: center;">
         <button onclick="myFunction()">Submit</button></p><br>  
        <script>
function myFunction() {
        var js_var = "The number of packets sent is: <?php echo $php_var; ?>";
                alert(js_var);
                    }
        </script>
     </font>
       </form>


      <?php
    if($_SERVER["REQUEST_METHOD"]== "POST"){
      if(isset($_POST["loops"])){
         $loops=$_REQUEST['loops'];
    }
 ?> 

Answer 4

您應該始終在頁面開頭使用PHP。 它是必需的，以便您可以獲得HTML中可用的變量。

    <form method ='post' action ="<?php echo $_SERVER['PHP_SELF']; ?>">

    <?php $loops = ''; ?>
    <?php if ($_SERVER["REQUEST_METHOD"] == "POST") {
            if (isset($_POST["loops"])) {
                $loops = $_REQUEST['loops'];
            }
        }
        ?>
        <b>
            <p>Number of packets to be sent:</p>
            <input type="text" name="loops" value="<?php echo $loops; ?>">
            <br><br>
        </b>
        <?php $php_var = $loops; ?>
        <p style="text-align: center;">
            <button onclick="myFunction()">Submit</button>
        </p>
        <br>  
        <script>
            function myFunction() {
                var js_var = "The number of packets sent is: <?php echo $php_var; ?>";
                alert(js_var);
            }
        </script>
</form>

Answer 5

您應該在$loop變量初始化后檢查是否有任何$_REQUEST['loops'] 。

所以代碼應該是

<?php
    $loops = "";

    if($_SERVER["REQUEST_METHOD"]== "POST"){
        if(isset($_POST["loops"])){
            $loops=$_REQUEST['loops'];
        }
    }
?>

<form method ='post' action ="<?php echo $_SERVER['PHP_SELF'];?>">

<b> <p>Number of packets to be sent:</p>
<input type="text" name="loops" value="<?php echo $loops;?>">
<br><br></b>

<?php
$php_var = $loops;?>


<p style="text-align: center;">
<button onclick="myFunction()">Submit</button></p><br>  
<script>
    function myFunction() {
            var js_var = "The number of packets sent is: <?php echo $php_var; ?>";
                    alert(js_var);
                        }
</script>
</font>
</form>