使用ajax将$_POST变量发送到php

var xhr = new XMLHttpRequest();
xhr.open("POST", "your_php_file.php", true);
xhr.setRequestHeader("Content-Type", "application/x-www-form-urlencoded");

xhr.onreadystatechange = function() {
  if (xhr.readyState === 4 && xhr.status === 200) {
    // 处理服务器返回的响应数据
    var response = xhr.responseText;
    console.log(response);
  }
};

var postData = "variable1=value1&variable2=value2"; // 根据实际情况构造POST数据
xhr.send(postData);

$variable1 = $_POST['variable1'];
$variable2 = $_POST['variable2'];

// 对接收到的数据进行处理
// ...

// 返回响应数据
$response = "处理结果";
echo $response;