Question

这是连接到MySQL数据库并执行CRUD操作的PHP文件的一部分，'echo'内部的'alert'函数未执行..为什么？：

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Answer 1

这是因为标头（'location：index.php'）； According to PHP:

请记住，必须先通过正常的HTML标签，文件中的空白行或从PHP发送任何实际输出，然后才能调用header（）。

Answer 2

不要回显js，只需关闭php标签并按原样编写

<?php
if (isset($_GET['del'])) {
        $id = $_GET['del'];
        ?>
       <script>
         alert("The record <?=$id?> will be deleted");
         </script>
       <?php

        mysqli_query($db, "DELETE FROM info WHERE id=$id");
        $_SESSION['message'] = "Address deleted!";
        header('location: index.php');
}
?>

Answer 3

对此不太确定，但我认为分号（;）告诉echo在此停止，因此echo只打开了脚本，但看不到其余的内容

尝试一下：

if (isset($_GET['del'])) {

        $id = $_GET['del'];
        echo '<script language="javascript">
         alert("The record"' . $id  .'"will be deleted")
         </script>';
        // exit;
        mysqli_query($db, "DELETE FROM info WHERE id=$id");
        $_SESSION['message'] = "Address deleted!";
        header('location: index.php');
}

Answer 4

您需要像这样更改代码。

alert("The record " + '. $id .' +" will be deleted");

或者您也可以将引号转义，例如：

alert("The record \" '. $id .' \" will be deleted");

Answer 5

警报的原因不是php函数，因此您需要在同一行中回显警报通过这种方式 echo'alert（“记录”'。$ id。'“将被删除”）';

Answer 6

您不能直接回显。试试这个

echo '<html><script> alert("The record"' . $id  .'"will be deleted")<script></html>';

Answer 7

先传回东西再重定向实际上是行不通的。也许您想代替回显该消息，然后用户可以单击“确定”按钮以重定向到索引页面。

if (isset($_GET['del'])) {
  $id = $_GET['del'];
  mysqli_query($db, "DELETE FROM info WHERE id=$id");
  $_SESSION['message'] = "Address deleted!";
  echo '<script>';
  echo 'function backToIndex() {';
  echo 'location.replace("https://www.yoursite.com");';
  echo '}';
  echo '</script>';
  echo '<div>';
  echo '<p>The record ' . $id . ' is deleted.</p>';
  echo '<button onclick="backToIndex()">ok</button>';
  echo '</div>';
}

如果希望用户在删除前进行确认，则可以将时间戳记或随机字符串存储在会话变量中，并检查是否已设置。如果没有，请确认。如果已设置，请删除。

<?php
if (isset($_GET['del'])) {
  $id = $_GET['del'];
  if (!isset($_SESSION['del_confirmed'])) {
    $_SESSION['del_confirmed'] = microtime();
  }
  if ($_GET['token'] === $_SESSION['del_confirmed']) {
    mysqli_query($db, "DELETE FROM info WHERE id=$id");
    $_SESSION['message'] = "Address deleted!";
    unset($_SESSION['del_confirmed']);
    header('location: index.php');
  } else {
?>

<script>
function backToIndex() {
  location.href= "index.php";
}
</script>

<div>
<p>Do you really want to delete record <?=$id?>?</p>
<form action="index.php" method="get">
<input type="text" name="del" value="<?=$id?>">
<input type="text" name="token" value="<?=$_SESSION['del_confirmed']?>">
<button type="submit">yes</button>
</form>
<button onclick="javascript:backToIndex();">no</button>
</div>

<?php
  }
}
?>

Answer 8

这将起作用。经过测试并为我工作。

if (isset($_GET['del'])) {
$id = $_GET['del'];
$alert = 'alert("The record' . $id  .'will be deleted");';
echo "<script type='text/javascript'>";
echo $alert;
echo "</script>";
}

Answer 9

尝试先关闭php，然后添加脚本标签。我在网上试过了

    <?php
    if (isset($_GET['del'])) {
        $id = $_GET['del'];
        ?>
       <script>
         alert("The record <?php echo $id ?> will be deleted");
         </script>
       <?php

        mysqli_query($db, "DELETE FROM info WHERE id=$id");
        $_SESSION['message'] = "Address deleted!";
        header('location: index.php');
}
?>

为什么以下代码中的警报未执行：？

9 个答案: