// 例: getCurrentPosition()

var locmarker = L.marker(mymap.getCenter()).addTo(mymap);
locmarker.bindPopup("捕捉中...").openPopup();

var nTrial = 100
function tryGetLOC() {
    navigator.geolocation.getCurrentPosition(
	onSuccess, onError,{
	    maximumAge: 0, });
}
function onSuccess(pos) {
    var latlng = L.latLng([pos.coords.latitude, pos.coords.longitude]);
    mymap.panTo(latlng);
    locmarker.setLatLng(latlng).setPopupContent(
	"ここは "+latlng+"です."
    ).openPopup();
}
function onError(err) {
    restN = "あと"+(--nTrial)+"回試行します。";
    locmarker.setPopupContent("捕捉失敗:"+restN).openPopup();
    if (nTrial > 0) {
	tryGetLOC();
    }
}
tryGetLOC()