从Javascript调用PHP文件（AJAX？）

Question

问题：

您好，我已经在线研究了AJAX，但我不太了解。我试图从javascript函数中调用php文件，不幸的是它无法正常工作。我正在尝试一切，但我仍然不明白。希望这里的人们可以以我的代码为例向我解释。

---

Javascript：

这是我要从以下位置调用文件的函数：

function countdownEnded() {
    //make serverscreen dissapear
        document.getElementById('serverScreenWrapper').style.display = 'none';
        document.getElementById('serverScreenWrapper').style.opacity = '0';
        document.getElementById("cashOutNumTwo").style.right = '150%';
        document.getElementById("cashOutNumOne").style.right = '150%';
//start Timer
        setInterval(gameTimer.update, 1000);
//make player move again
        socket.emit('4');
        socket.emit('6');
//make game appear
        document.getElementById('gameAreaWrapper').style.opacity = 1;
//play sound
        document.getElementById('spawn_cell').play();
//cut 5 cents from account - php function
        //CALL PHP FUNCTION HERE WITH AJAX
}

因此php文件基本上是| ../../../../subtract5.php |相对于其他文件。

---

PHP：

这是文件：

<?php
session_start();

$servername = "localhost";
$username = "myUser";
$password = "myPass";
$dbname = "myDBname";
$cash_amount = $_SESSION['cash_amount'];

// Create connection

$userid = $_SESSION['id'];

// You must enter the user's id here. /\

$conn = new mysqli($servername, $username, $password, $dbname);
// Check connection

if ($conn->connect_error) {
    die("Connection failed: " . $conn->connect_error);
}

// Fetch the existing value of the cash_amount against that particular user here. You can use the SELECT cash_amount from users where userid = $userid
$_SESSION['cash_amount'] -= 0.05;
$newAmount = $cash_amount - 0.05;

$sql = "UPDATE users SET cash_amount = $newAmount WHERE id = $userid";
$result = $conn->query($sql);

if($result)
{
   echo "5 cents have been subtracted!";
}
else
{
   echo mysqli_error($conn);
   session_start();
   session_unset();
   session_destroy();
}

$conn->close();
?>

结论：

如何从函数中调用此文件，作为奖励：如果我想将javascript变量发送到该文件以用于更新数据库，我该怎么做？

非常感谢您的帮助！

Answer 1

将这段代码写成您的javascript函数

function countdownEnded() {
       /* Your Code */
     $.ajax({
        type: "POST",
        url: '/subtract5.php',
        data: { },
        success: function (data) {
            alert(data);
        }
    });
}