Async Google Maps API v3 undefined is not a function

Question

I'm writing an app that loads Google Maps asynchronously with a hand-built framework.
When I load maps it will not load all of it for some reason and I'll end up with a Uncaught TypeError: undefined is not a function. I checked chrome inspector and found out that google.maps is a valid object, but it has none of its own properties. I manually call the "initialize function" well after the document has loaded. What am I doing wrong?!

Answer 1

You can't load the maps-API asynchronous with the well-known URL( http://maps.googleapis.com/maps/api/js?v=3&sensor=false )

When you take a look at the script-file, you'll see, that this is not the API that gets loaded, it's a loader that loads the API. The loader makes use of document.write() , what will lead you to unexpected results when called after the document has been loaded.

Furthermore the onload-event of the document doesn't wait for asynchronous loaded objects, it may come too quick.

You also cannot use the load-event of the script to invoke the initialize-function, because when it fires, the loader is loaded, not the maps-API.

What to do:
append a callback-parameter to the script-URL(with the name of the initialize-function as value)

http://maps.googleapis.com/maps/api/js?v=3&sensor=false&callback=initialize

Now you get a different loader which:

1. doesn't use document.write()
2. calls the callback-function(initialize) when the maps-API has been loaded

Demo: http://jsfiddle.net/doktormolle/7cu2F/

---

Related to the comment: seems the callback has to be a function attached to window directly. not cool google :)

There is another option, the google-API-loader which supports the usage of function-references (instead of function-names).

Sample, which loads the maps-API asynchronously, but only when there is an element with the ID map-canvas in the document, and then creates a map:

    window.addEventListener('load',function(){
      if(document.getElementById('map-canvas')){
        google.load("maps", "3",{
          callback:function(){
             new google.maps.Map(document.getElementById('map-canvas'), {
                center: new google.maps.LatLng(0,0),
                zoom: 3
              });
          }
        });     
      }
    },false);

      body,html,#map-canvas{
        height:100%;
        margin:0;
        padding:0;
        width:100%;
      }

<script src="https://www.google.com/jsapi?.js"></script>
<div id="map-canvas"></div>