How to get a php array index and use it in javascript

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);
}

Why don't you try this like $latArr[] = $lat; $longArr[] = $lon; . This way you don't need to keep track on index — Jigar7521
– Jigar7521, Commented Dec 6, 2016 at 9:33
To be honest, I don't really understand what you want to achieve. What exactly is the problem in your code? — Dragos
– Dragos, Commented Dec 6, 2016 at 9:37

Fky · Accepted Answer · 2016-12-06 09:40:50Z

3

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);

answered Dec 6, 2016 at 9:40

Fky

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1 Comment

Roman Granovsky Over a year ago

Ah, you were the first :)

Roman Granovsky · Accepted Answer · 2016-12-06 09:41:57Z

1

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

answered Dec 6, 2016 at 9:41

Roman Granovsky

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