Get google.maps.Map instance from a HTMLElement

Question

I have an existing map on a page. I can select that element using something along the lines of document.getElementById() to get the HTMLElement javascript object. Is it possible

Answer 1

I had a similar problem. All I wanted to do was to manipulate maps after they where created. I tried something like that (I think it will help you too). I've created function (more or less like this):

function load_map(el_id, lat, lng) {
  var point = new google.maps.LatLng(lat,lng);
  var myMapOptions = {
    scrollwheel:false,
    zoom: 15,
    center: point,
    mapTypeControl: true,
    mapTypeControlOptions: {
      style: google.maps.MapTypeControlStyle.DROPDOWN_MENU,
      position: google.maps.ControlPosition.RIGHT_TOP
    },
    navigationControl: true,
    navigationControlOptions: {
      style: google.maps.NavigationControlStyle.SMALL,
      position: google.maps.ControlPosition.LEFT_CENTER
    },
    mapTypeId: google.maps.MapTypeId.ROADMAP
  };
  var map = new google.maps.Map(document.getElementById(el_id),myMapOptions);
  var marker = new google.maps.Marker({
    draggable:true,
    map: map,
    position: point
  });
  return({
    container:map.getDiv(),
    marker:marker,
    mapa:map
  });
}

What this function does is after calling it to create a map in some container.

var mapa = load_map('mapa_container', 53.779845, 20.485712);

Function will return object containing some data used while making the map. After creating a map itself I can simply manipulate, in my case, marker on each map separately using mapa object, for example:

mapa.marker.setPosition(new google.maps.LatLng(20,30));
mapa.mapa.setCenter(new google.maps.LatLng(20,30));

This will change marker position and center map to the same coords. Notice that lng and lat values are different then while calling function that creates a map.

Hope that helps.

Answer 2

If you are using Google-map component from the Polymer project, you can get the existing map Dom like this:

var map = document.querySelector('google-map');

Once you have that, current instance of map can be accessed by:

var currentMapInstance = map.map;

Answer 3

You create an instance when you initialize a map;

var map = new google.maps.Map(document.getElementById("map_element"), options);

You use that instance whenever you want to do something like putting a marker, changing location, etc. It's not an HTMLElement object. However it has a getDiv() method, which gives you the html element it's operating on.

map.getDiv(); // in this case it returns the element with the id 'map_element'

Answer 4

You can get google.maps.Map object from DOM Element, with a slight trick.

When you initialize map object, you need to store the object on element's data attribute.

Example:

$.fn.googleMap = function (options) {
    var _this = this;

    var settings = $.extend({}, {
        zoom: 5,
        centerLat: 0,
        centerLon: 0
    }, options);

    this.initialize = function () {
        var mapOptions = {
            zoom: settings.zoom
        };

        var map = new google.maps.Map(_this.get(0), mapOptions);
        // do anything with your map object here,
        // eg: centering map, adding markers' events

        /********************************************
         * This is the trick!
         * set map object to element's data attribute
         ********************************************/
        _this.data('map', map);

        return _this;
    };
    // ... more methods

    return this;
};

After you define a map element, eg:

var mapCanvas = $('#map-canvas');
var map = mapCanvas.googleMap({
    zoom: 5,
    centerLat: 0,
    centerLong: 0
});
// ... add some pre-load initiation here, eg: add some markers
// then initialize map
map.initialize();

you can then get the map object later on by using element's ID, eg:

var mapCanvas = $('#map-canvas');
$('.location').on('click', function () {
    // google map takes time to load, so it's better to get
    // the data after map is rendered completely
    var map = mapCanvas.data("map");
    if (map) {
        map.panTo(new google.maps.LatLng(
            $(this).data('latitude'),
            $(this).data('longitude')
            ));
    }
});

By using this method, you can have multiple maps with different behaviors on a page.

Answer 5

You can't get google.maps.Map object from DOM Element ,on which Google Maps object have been constructed. google.maps.Map is just a wrapper, which controls DOM Element for viewing the map, and that element does not have reference to its wrapper.

If your problem is only the scope, make map as a property of window object, and it will be accessible from everywhere in your page. You can make 'map' as global by using one of these:

 window.map = new google.maps.Map(..) 

or

 map = new google.maps.Map(...) //AVOID 'var'