How to convert extracted PHP data to javascript array containing integer

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Extracting data from mysql and using them in javascript, instead of an array with integer I get a string with quotes like this:

"var latlong = [[38.4870556,68.8065556],[38.7059167,69.2994444]];"

What I have tried:

Here extracting data with PHP:

try {
    $db = new PDO("mysql:host=$servername;dbname=$dbname", $username, $password, array(
        PDO::MYSQL_ATTR_INIT_COMMAND => "SET NAMES utf8",
        PDO:: ATTR_DEFAULT_FETCH_MODE => PDO::FETCH_OBJ,
        PDO:: ATTR_ERRMODE => TRUE
    ));

} catch(PDOException $e) {
    die($e->getMessage());
}

$stmt = $db->prepare("SELECT latitude, longitude FROM  hydros WHERE latitude <> 0");
$stmt->execute();

$data = [];

$result = $stmt->fetchAll();
foreach ($result as $row) {
    $data [] = [(float)$row->latitude,(float)$row->longitude];
}

echo "var latlong = " . (!empty($data) ? json_encode($data)  : "]") . ";";

Then retrieving data with jQuery

	function latlongc(callback) {
    httpRequest = new XMLHttpRequest();
    httpRequest.onreadystatechange = function () {
        if (httpRequest.readyState === 4) { // request is done
            if (httpRequest.status === 200) { // successfully
                callback(httpRequest.responseText); // we're calling our method
            }
        }
    };
    httpRequest.open('GET', "latlong.php");
    httpRequest.send();
}

	latlongc(function (result) {
    
    latlong1 = result;
    console.log(latlong1);
});

Posted 21-May-19 21:22pm

Himjon

Updated 7-Jun-19 6:34am

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Richard MacCutchan 22-May-19 3:46am

Look at the last line of your php code, you present the result as a string.

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W∴ Balboos, *GHB* · Accepted Answer · 2019-05-23T03:49:00

Looking at that last line of php code:

echo "var latlong = " . (!empty($data) ? json_encode($data)  : "]") . ";";

Suppose the array is empty? Your output would be:

var latlong  = ];

which is obviously an error and could cause collateral mischief in other javascript.

Suppose it's not:
If you build the page with the javaScript before the page is served they're part of the page. Use as normal.
If, however, you put javaScript on your page with AJAX, be aware that new javaScript may not be actually available to your page if you just render the text.

Let's assume callback() already exists: It's getting what you'd expect[^] form JSON formed from a non-associative array. By this I mean you do not have indices.

You'll find this in the linked page:

Quote:
Non-associative array output as array: [[1,2,3]]
Non-associative array output as object: {"0":{"0":1,"1":2,"2":3}}

Hope this helps you find your missing int's (i.e., If I understand you correctly)

Himjon · Accepted Answer · 2019-06-07T06:35:00

Building GeoJSON file to use it with javascript.

# Build GeoJSON feature collection array
$geojson = array(
   'type'      => 'FeatureCollection',
   'features'  => array()
);

# Loop through rows to build feature arrays
while ($row = $stmt->fetch(PDO::FETCH_ASSOC)) {
    $properties = $row;
    # Remove long, lat and IFNULL fields from properties (optional)
    unset($properties['IFNULL']);
    unset($properties['longitude']);
    unset($properties['latitude']);
    $feature = array(
        'type' => 'Feature',
        'geometry' => array(
            'type' => 'Point',
            'coordinates' => array(
                (float)$row['longitude'],
                (float)$row['latitude']
            )
        ),
        'properties' => $properties
    );
    # Add feature arrays to feature collection array
    array_push($geojson['features'], $feature);
}

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

//Building var hydros to add it 
$hydros = "var hydros = ";

//Write to geoJSON file
$fp = fopen('data/hydros.geojson',  'w');
fwrite($fp, $hydros);
fwrite($fp, json_encode($geojson, JSON_UNESCAPED_UNICODE));
fclose($fp);

Then using "var hydros;" array in javascript:

<script src="data/hydros.geojson"></script>

Hope this will help others.

How to convert extracted PHP data to javascript array containing integer

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