Using Proj4JS for vector reprojection
http://openlayers.org/dev/examples/using-proj4js.html
HTML
<script src="https://cdnjs.cloudflare.com/ajax/libs/openlayers/2.13.1/OpenLayers.js"></script>
<script src="https://cdn.rawgit.com/cdnjs/cdnjs/master/ajax/libs/proj4js/1.1.0/proj4js-compressed.js"></script>
<h1 id="title">Using Proj4JS for vector reprojection</h1>
<p id="shortdesc">
</p>
JavaScript
(function($) {
Proj4js.defs["EPSG:31467"] = "+proj=tmerc +lat_0=0 +lon_0=9 +k=1 +x_0=3500000 +y_0=0 +ellps=bessel +datum=potsdam +units=m +no_defs";
var map, vector;
function init(){
var original=new OpenLayers.LonLat(7.841573,48.002718);
var wgs84=new OpenLayers.Projection("EPSG:4326");
var gk3=new OpenLayers.Projection("EPSG:31467");
console.log(gk3);
var ergebnis=original.transform(wgs84,gk3);
alert(ergebnis);
}
init();
})(jQuery);