PHP and javascript Array Literals

Question

I need help, sending data from the server.

$conn = new mysqli($servername, $username, $password, $dbname);
// Check connection
if ($conn->connect_error) {
 die("Connection failed: " . $conn->connect_error);
} 
$sql = "SELECT id, voltage/*, current_out, power ,temperature, reading_time*/ FROM SensorData GROUP BY id;";
$result = mysqli_query($conn,$sql);
$data1= array();
 
foreach ($result as $row) {
 $data1[] = $row;
}
 $result->close();

shaped

[{"id":"36","voltage":"16"},{"id":"37","voltage":"18"},{"id":"38","voltage":"20"},{"id":"39","voltage":"22"},{"id":"40","voltage":"26"},{"id":"41","voltage":"30"},{"id":"42","voltage":"32"},{"id":"43","voltage":"34"},{"id":"44","voltage":"36"},{"id":"45","voltage":"36"}] 

and I process but I don't know exactly how to approach individual parameters. you don't know where the problem is.

<script >
 
 $(document).ready(function(){
 $.ajax({
 url: "http://192.168.1.16/webput_to_mysql.php",
 method: "GET",
 success: function(data1) {
 console.log(data1);
 var voltage1 = [];
 var id1 = [];
 voltage1.push(data1[1].voltage);
 document.getElementById("demo").innerHTML = voltage1;
 }
 });
});
</script>

enter image description here

Answer 1

The problem is that the data is coming back as a string, and you're trying to read it as JSON. You can just add the dataType option to ajax, to tell jQuery how to handle things.

$.ajax({
 url: "http://192.168.1.16/webput_to_mysql.php",
 method: "GET",
 dataType: "json",
 ...
});

See the docs for more info.

Another option is to send the json header in PHP (before your echo json_encode...), which should help jQuery detect the type automatically:

header('Content-Type: application/json');