How pass session variable in javascript

If you are using that JavaScript function with a PHP file, you can do it:

...
var line2 = '<?php echo $_SESSION["line2"]; ?>';
var oline2 = '<?php echo $_SESSION["oline2"]; ?>';
...

To pass JavaScript variable to the PHP, you have to follow these steps:

1. Include JQuery Library in your page (if you don't have yet).
2. Create a PHP page to set the variables (ie: myPage.php).
3. Pass the JS variables with ajax (JQuery) to the myPage.php via POST.

myPage.php:

<?php
session_start();

$_SESSION['line2'] = $_POST['myVariable'];
$_SESSION['oline2'] = $_POST['anotherOne'];
...

In your JS function:

var sth = 'something...';
var sthMore = 'something more...';

$.ajax({
    method: "POST",
    url: "myPage.php",
    data: { myVariable: sth, anotherOne: sthMore }
}).done(function() {
     // alert('done!'); // here you can alert some message (if you want)
 });

Try this -

var variable = "<?php echo $_SESSION['variable'];?>";

yup.. get your session variable $_SESSION['line2'], $_SESSION['oline2']

<?php 
$line2 = $_SESSION['line2'];
$oline2= $_SESSION['oline2'];
?>

now save these value in html hidden type input

" /> " />

now call these hidden value in your javascript code..

<script>
var line2= $("#line2").val();
var oline2= $("#oline2").val();
</script>

Before using php code within javascript code you need to make sure that your javascript code is written in .php file or another file that can be rendered as php. It can not be placed in .js file

Try following code

function showLocation() {
            var geocoder, location1, location2, gDir;

            geocoder = new GClientGeocoder();
            gDir = new GDirections();
            GEvent.addListener(gDir, "load", function() {
                //var drivingDistanceMiles = gDir.getDistance().meters / 1609.344;
                var drivingDistanceKilometers = gDir.getDistance().meters / 1000;
               // var miles = drivingDistanceMiles ;
                var km = drivingDistanceKilometers;
                //document.getElementById('miles').value = miles;
                document.getElementById('km').value = km;

            });

geocoder.getLocations("<?php echo $_SESSION['line2'];?>", function (response) {
                if (!response || response.Status.code != 200)
                {
                    alert("Sorry, we were unable to geocode the first address");
                }
                else
                {
                    location1 = {lat: response.Placemark[0].Point.coordinates[1], lon: response.Placemark[0].Point.coordinates[0], address: response.Placemark[0].address};
                    geocoder.getLocations("<?php echo $_SESSION['oline2'];?>", function (response) {
                        if (!response || response.Status.code != 200)
                        {
                            alert("Sorry, we were unable to geocode the second address");
                        }
                        else
                        {
                            location2 = {lat: response.Placemark[0].Point.coordinates[1], lon: response.Placemark[0].Point.coordinates[0], address: response.Placemark[0].address};
                            gDir.load('from: ' + location1.address + ' to: ' + location2.address);
                        }
                    });
                }
            });
        }