Using the cluster strategy

As we have seen in the chapter's introduction, the behavior of vector layers is determined by the strategies we attach to them.

Imagine a scenario where we want to show all the museums in every city around the world. What will happen when the user navigates within the map and sets a zoom level to see the whole world? We simply see a cloud of points, all at the same place.

The solution to this problem is to cluster the features on each zoom level.

This recipe shows how easy it is to use the cluster strategy on a vector layer, which is responsible for clustering the features to avoid a situation similar to the one we just mentioned.

How to do it...

1. Create an HTML file and insert the following code in it:

   <!-- Map DOM element -->
   <div id="ch3_cluster" style="width: 100%; height: 100%;"></div>
   
   <!-- The magic comes here -->
   <script type="text/javascript">
       // Create the map using the specified DOM element
       var map = new OpenLayers.Map...