diff --git a/loc-chase2.js b/loc-chase2.js
index 15165d4..6d4a942 100644
--- a/loc-chase2.js
+++ b/loc-chase2.js
@@ -1,6 +1,8 @@
 document.addEventListener("DOMContentLoaded", () => {
 
-  var mymap = L.map("locationmap").setView([38.891, 139.824], 16);
+  const mapDiv = document.getElementById("locationmap");
+
+  var mymap = L.map(mapDiv).setView([38.891, 139.824], 16);
 
   L.tileLayer("https://{s}.tile.osm.org/{z}/{x}/{y}.png", {
     attribution:
@@ -10,11 +12,9 @@
   var locmarker = L.marker(mymap.getCenter()).addTo(mymap);
   locmarker.bindPopup("STARTおしてね").openPopup();
 
-  var nTrial = 100;
   var watchId = null;
 
   function stopLOC() {
-    console.log("watchId=" + watchId);
     if (watchId != null) {
       navigator.geolocation.clearWatch(watchId);
       document.getElementById("title").textContent = "stop";
@@ -28,14 +28,12 @@
     watchId = navigator.geolocation.watchPosition(
       onSuccess,
       onError,
-      { maximumAge: 0, timeout: 3000, enableHighAccuracy: true }
+      { enableHighAccuracy: true }
     );
     document.getElementById("title").textContent = "START!!";
   }
 
-
-  function updateLocation(lat, lng) {
-    const latlng = L.latLng(lat, lng);
+  function updateLocation(latlng) {
     mymap.panTo(latlng);
 
     const goalLat = 38.892;
@@ -45,7 +43,6 @@
     const dLng = Math.abs(latlng.lng - goalLng);
 
     let message;
-
     if (dLat < 0.0003 && dLng < 0.0003) {
       message = "🎉 GOAL!! 宝を見つけました！";
     } else if (dLat < 0.001 && dLng < 0.001) {
@@ -60,35 +57,34 @@
       .openPopup();
   }
 
-
   function onSuccess(pos) {
-    updateLocation(
+    const latlng = L.latLng(
       pos.coords.latitude,
       pos.coords.longitude
     );
+    updateLocation(latlng);
   }
 
-  function onError(err) {
-    var restN = "あと" + (--nTrial) + "回試行します。";
-    locmarker.setPopupContent("捕捉失敗:" + restN).openPopup();
-    if (nTrial <= 0) {
-      navigator.geolocation.clearWatch(watchId);
-    }
-  }
+  function onError() {}
 
-
-  mymap.on("mousedown touchstart", function (e) {
+  mapDiv.addEventListener("mousedown", (e) => {
     stopLOC();
-    updateLocation(
-      e.latlng.lat,
-      e.latlng.lng
-    );
+    const latlng = mymap.mouseEventToLatLng(e);
+    updateLocation(latlng);
   });
 
+  mapDiv.addEventListener("touchstart", (e) => {
+    stopLOC();
+    const touch = e.touches[0];
+    const latlng = mymap.mouseEventToLatLng(touch);
+    updateLocation(latlng);
+  });
+
+
   document.getElementById("start")
     .addEventListener("click", tryWatchLOC);
 
   document.getElementById("stop")
     .addEventListener("click", stopLOC);
 
-}, false);
+});