javascript - 具有半径 : controlling map output when there are no stores in the user's radius 的 Google Maps API v3 商店定位器

Question

我遵循了 Google map 商店定位器教程 https://developers.google.com/maps/articles/phpsqlsearch_v3并构建了一个定位器，它获取用户的位置和半径，然后输出用户位置半径范围内的所有商店位置。在大多数情况下，它是有效的!

我的问题是，当我输入位置和半径并且该半径内没有商店时，我的定位器会将 map 居中放置在太平洋中部。

我尽力研究了其他商店定位器问题，但它们都是关于让定位器本身发挥作用的。如果我遗漏了什么，我深表歉意!另外，我是 javascript 的初学者，因此非常感谢代码背后的逻辑答案!

谢谢!

function searchLocationsNear(center) {
 clearLocations();

 var radius = document.getElementById('radiusSelect').value;
 var searchUrl = 'storelocator_getXML.php?lat=' + center.lat() + '&lng=' + center.lng() + '&radius=' + radius;
 downloadUrl(searchUrl, function(data) {
   var xml = parseXml(data);
   var markerNodes = xml.documentElement.getElementsByTagName("marker");
   var bounds = new google.maps.LatLngBounds();
   for (var i = 0; i < markerNodes.length; i++) {
     var name = markerNodes[i].getAttribute("name");
     var address = markerNodes[i].getAttribute("address");
     var phone = markerNodes[i].getAttribute("phone");
     var fax = markerNodes[i].getAttribute("fax");
     var directions = markerNodes[i].getAttribute("directions");
     var distance = parseFloat(markerNodes[i].getAttribute("distance"));
     var latlng = new google.maps.LatLng(
      parseFloat(markerNodes[i].getAttribute("lat")),
      parseFloat(markerNodes[i].getAttribute("lng")));

     createOption(name, address, distance, i);
     createMarker(latlng, name, address, phone, fax, directions);
     bounds.extend(latlng);
   }
   map.fitBounds(bounds);
   locationSelect.style.visibility = "visible";
   locationSelect.onchange = function() {
     var markerNum = locationSelect.options[locationSelect.selectedIndex].value;
     google.maps.event.trigger(markers[markerNum], 'click');
   };
  });
}

Answer 1

经过多次试验和错误后，我突然灵机一动，找到了放置 if/else 语句的位置，以使我的 map 远离太平洋:

function searchLocationsNear(center) {
 clearLocations();

 var radius = document.getElementById('radiusSelect').value;
 var searchUrl = 'storelocator_getXML.php?lat=' + center.lat() + '&lng=' + center.lng() + '&radius=' + radius;
 downloadUrl(searchUrl, function(data) {
   var xml = parseXml(data);
   var markerNodes = xml.documentElement.getElementsByTagName("marker");

我在这里放了一个 if 语句。抓取选定半径内的所有标记位置后就说，如果有标记继续正常:

   if(markerNodes.length>0){

   var bounds = new google.maps.LatLngBounds();
   for (var i = 0; i < markerNodes.length; i++) {
     var name = markerNodes[i].getAttribute("name");
     var address = markerNodes[i].getAttribute("address");
 var phone = markerNodes[i].getAttribute("phone");
 var fax = markerNodes[i].getAttribute("fax");
 var directions = markerNodes[i].getAttribute("directions");
     var distance = parseFloat(markerNodes[i].getAttribute("distance"));
     var latlng = new google.maps.LatLng(
          parseFloat(markerNodes[i].getAttribute("lat")),
          parseFloat(markerNodes[i].getAttribute("lng")));

     createOption(name, address, distance, i);
     createMarker(latlng, name, address, phone, fax, directions);
     bounds.extend(latlng);
    }
    map.fitBounds(bounds);

在这里，我把其他的放在半径内没有标记时要做什么:

  } else {
    alert('Sorry, there are no stores that close to your location. Try expanding your search radius.');
   }

   locationSelect.style.visibility = "visible";
   locationSelect.onchange = function() {
     var markerNum = locationSelect.options[locationSelect.selectedIndex].value;
     google.maps.event.trigger(markers[markerNum], 'click');
   };

 });
}