我正在尝试转换mqtt字符串并将它们添加到mysql中，我已经成功地转换字符串并使它们在chrome控制台中正确显示，但是我丢失了javascript和php之间传递数据的位。
我在这个网站上尝试过其他问题中概述的一些东西，但我可以让它们工作，我尝试过使用ajax，但又无法让它工作我哪里做错了或我遗漏了什么？
下面的所有代码都在服务器端运行。

var hostname = "127.0.0.1";
var port = 1884;
// Create a client instance
var client = new Paho.MQTT.Client(hostname, Number(port), "clientId");

// set callback handlers
client.onConnectionLost = onConnectionLost;
client.onMessageArrived = onMessageArrived;

// connect the client
client.connect({
    onSuccess: onConnect
});

// called when the client connects
function onConnect() {
    // Once a connection has been made, make a subscription and send a message.
    console.log("onConnect");
    client.subscribe("test");
}

// called when the client loses its connection
function onConnectionLost(responseObject) {
    if (responseObject.errorCode !== 0) {
        console.log("onConnectionLost:" + responseObject.errorMessage);
    }
}

// called when a message arrives
function onMessageArrived(message) {        

var raw = message.payloadString;
message.length = raw.length;
message.raw = raw;
var data = {};

data.major = raw.slice(-10,-4);
data.mac = raw.substring(5,17);
data.hostname = raw.substring(18,30);
data.minor = raw.slice(-8,-4);

var str = data.hostname;
var location = str.replace(`C129E53D0F45`, `PINK`)
        .replace(`FD139CD46385`, `DARKORANGE`)
        .replace(`EB72F2609789`, `DEEPSKYBLUE`)
        .replace(`DBECEE45AE6F`, `RED`)
        .replace(`E47D6D760A7F`, `WHITE`)
        .replace(`C3D7EDB7EF28`, `WHITE`)
        .replace(`E3A3BD636EA3`, `GREEN`)
        .replace(`D6F579FC35C9`, `YELLOW`);

var beacon = parseInt(data.minor ,16);

 var topic2 = ('[value="'+location+','+beacon+', '+data.mac+'"]')
    console.log("Message arrived: topic=" + message.destinationName + ",  message=" + topic2);

 }

</script>
 <?php
 $servername = "127.0.0.1";
 $username = "user";
 $password = "password";
 $dbname = "test";

 // Create connection
 $conn = new mysqli($servername, $username, $password, $dbname);
 // Check connection
 if ($conn->connect_error) {
die("Connection failed: " . $conn->connect_error);
 }

 $sql = "INSERT INTO test.track (`location`,`beacon`, `mac`) VALUES ('+location+','+beacon+', '+data.mac+')";

 if ($conn->query($sql) === TRUE) {
echo "New record created successfully";
 } else {
echo "Error: " . $sql . "<br>" . $conn->error;
 }

 $conn->close();
 ?>