Openlayers - Get extent of WFS vector layer and zoom to that extent when map

I would like to do the following:

1) While loading an OpenLayers map object get the lat/long Bounding Box of a WFS vector layer served from GeoServer. 2) Use the extent from the WFS vector layer to zoom so the entire layer is viewable.

This is the script I have now that uses the lat/longs from the WFS vector and then zooms. This script works fine. I have a javascript function where the map and controls are created in the onLoad of the html Body tag. At the end of the script I call the loadZoomTo() function which then calls this line of script;

function zoomOnLoad() {
    this.map.setCenter(new OpenLayers.Bounds(-79.8961,41.1,-78.80809,42.2).getCenterLonLat(), 10);  
}

In this script I have the lat/longs hard-coded but I need to be able to change these interactively depending on what option the user selects when he enters the application. If I remove the hard-coded lat/longs and try to replace them with something like this:

function zoomOnLoad() {
this.map.setCenter(new OpenLayers.Bounds(mLayers[a].getDataExtent()).getCenterLonLat(), 0);
}

it fails. I have also tried the event handler method as detailed here: OpenLayers, zoom to vector layer extent

but all I get is the html of the page with none of the OpenLayers stuff. No map, no controls etc..

Any suggestions would be appreciated.

Answer

After struggling with it for about 6 hours I was able to get it to work. Here is the script I used to solve the problem:

lyrstands = new OpenLayers.Layer.Vector("Stands 1stQ 2012",

{ 
    strategies: [new OpenLayers.Strategy.BBOX()],
    eventListeners: {           
        'loadend': function (evt) {//THE LOADEND EVENT LISTENER - WHEN THE LAYER IS DONE LOADING...
            map.zoomToExtent(lyrstands.getDataExtent());//ZOOM TO ITS EXTENT!
            }//END OF THE LOADEND EVENT
    },//END OF THE eventListeners BLOCK
    protocol: new OpenLayers.Protocol.WFS({
        url: "/geoserver/wfs",
        featureType: "Stands_1stQ2012",

        featureNS: "http://000.000.000.000:8080/OH_Layers",
        geometryName: "the_geom",
        version: "1.1.0"
    })
});