javascript - 从 php 重定向后无法运行 <Script>

Question

我有两个名为index.php 和uploadcover.inc.php 的文件。一切工作正常，除了如果上传因任何 if-else 条件失败而执行的脚本标记除外。这是代码:

index.php =>

      <form action="include/uploadcover.inc.php" method="post" enctype="multipart/form-data">
        <input type="file" name="file" id="cover-upload" style="display:none" onchange="this.form.submit();">
        <label for="cover-upload" class="fa fa-camera fa-2x" aria-hidden="true"></label>
      </form>

uploadcover.inc.php =>

<?php
session_start();
include_once 'dbh.inc.php';
$sessionid = $_SESSION['u_id'];

    $filename = "../profile/cover".$sessionid.".*";
    $fileinfo = glob($filename);
    $fileExt= explode('.',$fileinfo[0]);
    $fileActualExt= $fileExt[3];
    $file = "../profile/cover".$sessionid.".".$fileActualExt;
    if(!unlink($file)){
      echo "File not deleted";
    } else {
      "File deleted";
    }

    $sql = "UPDATE coverimg SET status=1 WHERE user_id='$sessionid';";
    mysqli_query($conn,$sql);

  $file= $_FILES['file'];
  $fileName= $file['name'];
  $fileTmpName= $file['tmp_name'];
  $fileSize= $file['size'];
  $fileError= $file['error'];
  $fileType= $file['type'];

  $fileExt = explode('.',$fileName);
  $fileActualExt = strtolower(end($fileExt));

  $allowed = array('jpg','jpeg','png','gif');

  if(in_array($fileActualExt,$allowed)){
    if($fileError=== 0){
      if($fileSize<3145728){
        $fileNameNew = "cover".$sessionid.".".$fileActualExt;
        $fileDestination = '../profile/'.$fileNameNew;
        move_uploaded_file($fileTmpName,$fileDestination);
        $sql = "UPDATE coverimg SET status=0 WHERE user_id='$sessionid'";
        mysqli_query($conn,$sql);
        header("Location: ../index.php?upload=success");
      } else {
        header("Location: ../index.php?upload=size_exceeded_3MB");
        exit();
        echo "<script>alert('File should be less than 3MB!')</script>";
      }
    } else {
      header("Location: ../index.php?upload=error");
      exit();
      echo "<script>alert('Error uploading the file!')</script>";
    }
  } else{
    header("Location: ../index.php?upload=typeerror");
    exit();
    echo "<script>alert('Filetype not supported!')</sc
    ript>";
  }

注意:我尝试了 die()、exit() 并删除了它们，以防它在重定向到 index.php 后执行脚本，但它不起作用。

Answer 1

重定向告诉客户端他们要查找的原因可以在不同的 URL 中找到。然后，客户端请求其他 URL 并显示该文档。

您不能同时说“这是您应该显示的文档”和“您应该显示的文档可以在这里找到”。二者择其一。