The vector layer, by itself, is a layer like the other layers we've discussed so far. To really get the most out of the vector layer class, we'll be working mostly with other classes. For example, to get a basic example working (like the first one in this chapter), we will make use of at least one other class—the ol.source.Source class—to read features from a particular vector format. In fact, under the hood, OpenLayers was using a format, features, geometries, and some styles for this example. All of this happens automatically for the simplest case of drawing some vector data, but in practice, it's necessary to understand how these other classes function as well to get the most out of OpenLayers.

Before we get into too much detail, let's cover the vector layer class, ol.layer.Vector, itself. It is a direct subclass of ol.layer.Layer and inherits its methods and observable properties. Refer to Chapter 2, Key Concepts in OpenLayers if you need a refresher on those methods.

var layer = new ol.layer.vector(options);