我还有一个主意。

提供下载文件的PHP文件的URL。 然后你必须通过ajax触发相同的URL，我检查了这第二个请求只在你的第一个请求完成下载文件后才给出响应。所以你可以得到它的事件。

它正在通过ajax处理同样的第二个请求。

你可以使用serialize。下面是一个例子。

$("#submit_btn").click(function(){
    $('.error_status').html();
        if($("form#frm_message_board").valid())
        {
            $.ajax({
                type: "POST",
                url: "<?php echo site_url('message_board/add');?>",
                data: $('#frm_message_board').serialize(),
                success: function(msg) {
                    var msg = $.parseJSON(msg);
                    if(msg.success=='yes')
                    {
                        return true;
                    }
                    else
                    {
                        alert('Server error');
                        return false;
                    }
                }
            });
        }
        return false;
    });

我想分享一个详细的方法，如何张贴与PHP + Ajax以及错误抛出返回失败。

首先，创建两个文件，例如form.php和process.php。

我们将首先创建一个表单，然后使用jQuery .ajax()方法提交。其余的将在评论中解释。

form.php

<form method="post" name="postForm">
    <ul>
        <li>
            <label>Name</label>
            <input type="text" name="name" id="name" placeholder="Bruce Wayne">
            <span class="throw_error"></span>
            <span id="success"></span>
       </li>
   </ul>
   <input type="submit" value="Send" />
</form>

使用jQuery客户端验证表单并将数据传递给process.php。

$(document).ready(function() {
    $('form').submit(function(event) { //Trigger on form submit
        $('#name + .throw_error').empty(); //Clear the messages first
        $('#success').empty();

        //Validate fields if required using jQuery

        var postForm = { //Fetch form data
            'name'     : $('input[name=name]').val() //Store name fields value
        };

        $.ajax({ //Process the form using $.ajax()
            type      : 'POST', //Method type
            url       : 'process.php', //Your form processing file URL
            data      : postForm, //Forms name
            dataType  : 'json',
            success   : function(data) {
                            if (!data.success) { //If fails
                                if (data.errors.name) { //Returned if any error from process.php
                                    $('.throw_error').fadeIn(1000).html(data.errors.name); //Throw relevant error
                                }
                            }
                            else {
                                    $('#success').fadeIn(1000).append('<p>' + data.posted + '</p>'); //If successful, than throw a success message
                                }
                            }
        });
        event.preventDefault(); //Prevent the default submit
    });
});

现在我们来看看process.php

$errors = array(); //To store errors
$form_data = array(); //Pass back the data to `form.php`

/* Validate the form on the server side */
if (empty($_POST['name'])) { //Name cannot be empty
    $errors['name'] = 'Name cannot be blank';
}

if (!empty($errors)) { //If errors in validation
    $form_data['success'] = false;
    $form_data['errors']  = $errors;
}
else { //If not, process the form, and return true on success
    $form_data['success'] = true;
    $form_data['posted'] = 'Data Was Posted Successfully';
}

//Return the data back to form.php
echo json_encode($form_data);

项目文件可以从http://projects.decodingweb.com/simple_ajax_form.zip下载。

如果你想用jQuery Ajax发送数据，那么就不需要表单标签和提交按钮

例子:

<script>
    $(document).ready(function () {
        $("#btnSend").click(function () {
            $.ajax({
                url: 'process.php',
                type: 'POST',
                data: {bar: $("#bar").val()},
                success: function (result) {
                    alert('success');
                }
            });
        });
    });
</script>

<label for="bar">A bar</label>
<input id="bar" name="bar" type="text" value="" />
<input id="btnSend" type="button" value="Send" />

自从引入了Fetch API，就没有理由再用jQuery Ajax或xmlhttprequest来实现了。要POST表单数据到php脚本在香草JavaScript你可以做以下:

异步函数postData() { 尝试{ Const res = await fetch('../php/contact.php'， { 方法:“文章”, new FormData(document.getElementById('form')) }) if (!res.ok)抛出新的错误('网络响应不正常'); } catch (err) { console.log (err) ｝ ｝ <form id="form" action="javascript:postData()" > <input id="name" name="name" placeholder=" name" type="text" required> <input type="submit" value=" submit" > > < /形式

下面是一个非常基本的php脚本示例，它获取数据并发送电子邮件:

<?php
    header('Content-type: text/html; charset=utf-8');

    if (isset($_POST['name'])) {
        $name = $_POST['name'];
    }

    $to = "test@example.com";
    $subject = "New name submitted";
    $body = "You received the following name: $name";
    
    mail($to, $subject, $body);

这是使用ajax在HTML中填充选择选项标签的代码，而XMLHttpRequest和API是用PHP和PDO编写的

conn.php

<?php
$servername = "localhost";
$username = "root";
$password = "root";
$database = "db_event";
try {
    $conn = new PDO("mysql:host=$servername;dbname=$database", $username, $password);
    $conn->setAttribute(PDO::ATTR_ERRMODE, PDO::ERRMODE_EXCEPTION);
} catch (PDOException $e) {
    echo "Connection failed: " . $e->getMessage();
}
?>

category.php

<?php
 include 'conn.php';
try {
    $data = json_decode(file_get_contents("php://input"));
    $stmt = $conn->prepare("SELECT *  FROM events ");
    http_response_code(200);
    $stmt->execute();
    
    header('Content-Type: application/json');

    $arr=[];
    while($value=$stmt->fetch(PDO::FETCH_ASSOC)){
        array_push($arr,$value);
    }
    echo json_encode($arr);
   
  } catch(PDOException $e) {
    echo "Error: " . $e->getMessage();
  }

script.js

var xhttp = new XMLHttpRequest();
xhttp.onreadystatechange = function () {
    if (this.readyState == 4 && this.status == 200) {
        data = JSON.parse(this.responseText);

        for (let i in data) {


            $("#cars").append(
                '<option value="' + data[i].category + '">' + data[i].category + '</option>'

            )
        }
    }
};
xhttp.open("GET", "http://127.0.0.1:8000/category.php", true);
xhttp.send();

index . html

<!DOCTYPE html>
<html lang="en">

<head>
    <meta charset="UTF-8">
    <meta http-equiv="X-UA-Compatible" content="IE=edge">
    <meta name="viewport" content="width=device-width, initial-scale=1.0">
    <link rel="stylesheet" href="style.css">
    <script src="https://code.jquery.com/jquery-3.6.0.min.js"
        integrity="sha256-/xUj+3OJU5yExlq6GSYGSHk7tPXikynS7ogEvDej/m4=" crossorigin="anonymous"></script>
    <title>Document</title>
</head>

<body>
    <label for="cars">Choose a Category:</label>

    <select name="option" id="option">
        
    </select>
    
    <script src="script.js"></script>
</body>

</html>