如何获取php数组索引并在javascript中使用它

Question

I have a PHP script that returns a latitude and longitude from the database.

Then I have a Javascript loop that loops according to the number of rows the PHP query returns and populate my data object with the logitude and latitude at a given index. The challenge now is - how do I get the index without hard coding it?

PHP

$DBhost = 'localhost';
$DBuser = 'root';
$DBpass = '';
$DBname = 'symptoms';

$con = mysqli_connect($DBhost, $DBuser, $DBpass) or die(mysql_error());
mysqli_select_db($con, $DBname);

$query = mysqli_query($con, 'SELECT latitude,longitude FROM markers') or die(mysql_error());

$longArr = array();
$latArr = array();
$count = 0;

while ($row = mysqli_fetch_array($query)) {
    $lat = $row['latitude'];
    $lon = $row['longitude'];

    $latArr[$count] = $lat;
    $longArr[$count] = $lon;

    ++$count;
}

JavaScript

var latArr = [];
var longArr = [];
var markersD = [];
var num = <?php echo $count ?>;

for (var i = 0; i < num; i++) {
  var data = {
    lat: '<?php echo $latArr[1]?>',
    lon: '<?php echo $longArr[1]?>'
  }
  console.log(data);
}

Answer 1

You have to create json object via php

while($row = mysqli_fetch_array($query))
{
    $json[] = array('lat' => $row['latitude'], 'lon' => $row['longitude']);
}
$json_string = json_encode($json);

=== JS ===

var data = <?php echo json_string; ?>;
console.log(data);

Answer 2

You can put all your coords in one array

$coords = array();
while($row = mysqli_fetch_array($query))
{
    $coords[] = array(
        'latitude' => $row['latitude'],
        'longitude' => $row['longitude'],
    )
}

and pass it to the js as a JSON object

var data = <?php echo json_encode($coords) ?>;
console.log(data);

All data you need should be available in the javascript