Why does an OpenLayers map.getNumLayers() return 0 even though I've added a layer?

Question

When I try the following code, OpenLayers returns a zero result. What have I done wrong, here?

var map;

function loadMap () {

    // Based on example code: view-source:
    //     http://openlayers.org/dev/examples/vector-formats.html

    map = new OpenLayers.Map(el);
    var googleStreetMap = new OpenLayers.Layer.Google('Google Street Map', 
                                                      { numZoomLevels: 20 });
    map.addLayers(googleStreetMap);
    var result = map.getNumLayers(); // Result == 0 :sad-panda:            
}

In the code above, I thought that the map.getNumLayers() should return 1 - considering i've asked to add a google street map.

Why is it returning zero, please?

UPDATE: something else to note: there is also no baseLayer :( I thought this would be the base layer???

Answer 1

I think it's because addLayers expects an array of layers. If you just want to add a single layer, you should use map.addLayer instead. Or you could give addLayers what it wants:

map.addLayers([googleStreetMap]);

I hope that helps.