Using JS Variable in Twig

Question

i need to use a JS Variable in in Twig.

I already found this attempt and i tried it in my code below but i didn't work, the whole map won't render at all. But it will if i remove the part between "var polylineCoordinates" and "polyline.setMap(map);".

My task is to draw a polyline from the lat/lon Data Pois within a Turn.

I posted the complete Code for the map down below.

<script type="text/javascript">
        function initialize() {
               var mapOptions = {
                   center: new google.maps.LatLng({{ turn.pois[0].lat }}, {{ turn.pois[0].lon }}),
                   zoom: 9,
                   mapTypeId: google.maps.MapTypeId.ROADMAP
               };

               var map = new google.maps.Map(document.getElementById("map_canvas"),
               mapOptions);

               var i;
               var polylineCoordinates = new Array[];
               for (i = 0; i < {{ turn.pois }}; ++i) {
                   var lat = {{ turn.pois["PLACEHOLDER"].lat }};
                   var lon = {{ turn.pois["PLACEHOLDER"].lon }};
                   polylineCoordinates.push(new google.maps.LatLng(lat.replace("PLACEHOLDER", i), lon.replace("PLACEHOLDER", i)));
                   };
               var polyline = new google.maps.Polyline({
                   path: polylineCoordinates,
                   geodesic: true,
                   strokeColor: '#FF0000',
                   strokeOpacity: 1.0,
                   strokeWeight: 2
               });
               polyline.setMap(map);
               }

         google.maps.event.addDomListener(window, 'load', initialize);
</script>

Also i'd really like some advice in general JS Coding if there's something missing or could be improved with my Code, im pretty new to JS

EDIT

I edited the Code now with the following

var polylineCoordinates = [];                
for (i = 0; i < {{ turn.pois|length }}; ++i) {
                    var lat = {{ turn.pois[0].lat }};
                    var lon = {{ turn.pois[0].lon }};
                    polylineCoordinates.push(new google.maps.LatLng(lat.replace(0, i), lon.replace(0, i)));
                };

Just for explaination for People that'll see this Question in a future time: I needed to add the |length at {{ turn.pois|length }} so it will compare with an intiger that stands for all elements in the collection "pois". Without the |length filter i would compare against the Collection/obejcts which of course won't work.

Further i needed to remove the "PLACEHOLDER" string because Twig will be parsed long before JS will even start running. So i need to give a legit default value, like [0]. (the first element in the collection)

The map is rendering now, but without the Polyline. I'm guessing that the replace() isn't working.

EDIT2

I just checked if the Polyline will draw if i use dummydata, so i just tried following:

        var polylineCoordinates = [
            new google.maps.LatLng(54.180260, 12.098421),
            new google.maps.LatLng(54.180348, 12.198463),
            new google.maps.LatLng(54.256842, 12.324694),
            new google.maps.LatLng(54.328642, 12.468212)
        ];
        /*for (i = 0; i < {{ turn.pois|length }}; ++i) {
            var lat = {{ turn.pois[0].lat }};
            var lon = {{ turn.pois[0].lon }};
            polylineCoordinates.push(new google.maps.LatLng(lat.replace(0, i), lon.replace(0, i)));
        };*/

It perfectly worked! So my problem is the way to replace the [0] with the i Variable from JavaScript. If needed i can post the generated JS Code also!

var polylineCoordinates = new Array[]; isn't valid JS, it should either be var polylineCoordinates = new Array(); or preferably var polylineCoordinates = [];. I'd say check for JS errors. It might also be beneficial to add the generated JS code to your question — duncan
– duncan, Commented Apr 29, 2014 at 8:26
Thanks for that, i edited the question and the code! :) But the Polyline won't render, just the map. But that's more than i got before — KhorneHoly
– KhorneHoly, Commented Apr 29, 2014 at 8:52
Don't you just need to create your LatLng like so? polylineCoordinates.push(new google.maps.LatLng(lat, lon)); — duncan
– duncan, Commented Apr 29, 2014 at 10:46
... and when you create lat and lon, use [i] instead of [0]: var lat = {{ turn.pois[i].lat }}; — duncan
– duncan, Commented Apr 29, 2014 at 10:48
That throws an error because he the Variable "i" is not available at the time the twig is created, because Twig is based on PHP :/ — KhorneHoly
– KhorneHoly, Commented Apr 29, 2014 at 11:16

pomaxa · Accepted Answer · 2014-04-29 11:08:04Z

0

Why do you need to use js variables in Twig? It's dirty and in your case it is useless. I suggest to fetch all coords with ajax before drawing polyine. It will be like:

 jQuery.ajax({
     url:    'http://example.com/getCoords',
     dataType: 'json'

     success: function(result) {
         //your array with coords;
         var polylineCoordinates = [];
                      console.log(result); //just to see what we have
                      $.each(result, function(i, item) {
                          polyineCoordinates = new google.maps.LatLng(item.lat, item.lng);
                      });
              },
     async:   false
});

and after this, - you can draw.

answered Apr 29, 2014 at 11:08

pomaxa

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4 Comments

KhorneHoly Over a year ago

I wanted to use Twig because all the data i would need to draw the map are already provided by Twig because i need them for the function of the page. I wanted to decrease Requests by doing it with twig, but i guess there is no other possibility expect Ajax. Thanks! :)

pomaxa Over a year ago

@KhorneHoly there is, the simplest I know, is to create string representation of js array in twig, and use eval. i.e. <script>eval('{{twigVar}}')</script> . But ajax method is better cuz it is more flexible, and you always can cache ajax responses.

KhorneHoly Over a year ago

Thanks for that, i keep it in mind :) But i already built it in Ajax, i agree with you. I was just curious if it is possible with twig and JS.

pomaxa Over a year ago

In short - yes it is. But I do not know case, when it will be good solution.

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