javascript - 显示另一个文件中操作文件内的警报消息

Question

所以我有这个 php 操作文件:

<?php
session_start();
require 'config.php';
if (isset($_POST['action']) && $_POST['action'] == 'signup') {

    $stmt1 = "SELECT * FROM users where username='" . $_POST['username'] . "'";
    $ret1 = mysqli_query($conn, $stmt1);
    $rowcount1 = mysqli_fetch_assoc($ret1);
    if (empty($rowcount1)) {


        $query = "INSERT INTO users (username, password, email, cpf)VALUES( '" . $_POST['username'] . "', '" . $_POST['password'] . "', '" . $_POST['email'] . "', '" . $_POST['cpf'] . "')";
        //echo $query;exit;
        echo  mysqli_query($conn, $query);
    } else {
        header("Location:signup.php");
        echo '<script language="javascript">';
        echo 'alert("User is already registered.")';
        echo '</script>';
    }
}

这个 else 语句变为 true，因为我可以在控制台中看到它，但是，我试图在另一个名为“signup.php”的文件中显示此警报消息。

我想在这个小 div 内显示警报消息:

<div class="cont">

</div>

我尝试用“header(”Location:signup.php”);”来做到这一点正如您所看到的，但不知道如何使其工作。

关于如何做到这一点有什么想法吗？

Answer 1

Header('Location:') 将重定向用户的浏览器。由于浏览器正在重定向，网页上不会显示任何其他内容。您需要将标签添加到页面signup.php。

<?php
session_start();
require 'config.php';
if (isset($_POST['action']) && $_POST['action'] == 'signup') {

    $stmt1 = "SELECT * FROM users where username='" . $_POST['username'] . "'";
    $ret1 = mysqli_query($conn, $stmt1);
    $rowcount1 = mysqli_fetch_assoc($ret1);
    if (empty($rowcount1)) {


        $query = "INSERT INTO users (username, password, email, cpf)VALUES( '" . $_POST['username'] . "', '" . $_POST['password'] . "', '" . $_POST['email'] . "', '" . $_POST['cpf'] . "')";
        //echo $query;exit;
        echo  mysqli_query($conn, $query);
    } else {
    // THE BROWSER IS HAS BEEN REDIRECTED TO signup.php
        header("Location:signup.php");

    // THIS ISN'T DISPLAY IN THE BROWSER BECAUSE THE BROWSER IS BEING REDIRECTED
        echo '<script language="javascript">';
        echo 'alert("User is already registered.")';
        echo '</script>';
    }
}