Geolocation using ClojureScript

geolocation.cljs

  (def urls (array "http://a.tile.openstreetmap.org/${z}/${x}/${y}.png"
                   "http://b.tile.openstreetmap.org/${z}/${x}/${y}.png"
                   "http://c.tile.openstreetmap.org/${z}/${x}/${y}.png"))

  (def OSM (js/OpenLayers.Layer.XYZ. "OSM (with buffer)" urls (extend-object! (js-obj) {"transitionEffect" "resize"
                                                                                        "buffer" 2
                                                                                        "wrapDateLine" true
                                                                                        "sphericalMercator" true})))

  (def plot (js/OpenLayers.Map. (extend-object! (js-obj) {"div" "plot"
                                                          "layers" (array OSM)
                                                          "center" (array 0 0)
                                                          "zoom" 3
                                                          "controls" (array (js/OpenLayers.Control.Navigation. (extend-object! (js-obj) {"dragPanOptions" (extend-object! (js-obj) {"enableKinetic" true})}))
                                                                            (js/OpenLayers.Control.PanZoom.)
                                                                            (js/OpenLayers.Control.LayerSwitcher.))})))

  ; Geolocation
  (defn geolocation [position]
    (def longitude (.-longitude js/position.coords))
    (def latitude (.-latitude js/position.coords))
    (def projection (js/OpenLayers.Projection. "EPSG:4326"))
    (def center (.transform (js/OpenLayers.LonLat. longitude latitude) projection (.getProjectionObject plot)))
    (.setCenter plot center 18))

  (.getCurrentPosition js/navigator.geolocation. geolocation)