等待Loop完成，然后再将值传递到javascript（还包括Google Maps）中。
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我不太使用JavaScript，因此对回调和响应不太熟悉。我正在使用谷歌地图来绘制出点A和点X，Y，Z之间的距离。问题是，我想使用JavaScript来确定X，Y，Z点中最接近A的点，它们映射出它们之间的方向。
我的代码正在运行。我可以算出所有3个目的地中最短的距离，但是我对这种愚蠢的外观感到困惑。
您会看到，Google使用异步回调将数据提供给浏览器，并且如果我运行for循环来逐个检查所有3个目的地，则会得到错误的结果。
这是代码：
var maxDistance = 99999999999;
var destn;
for (var i = 0; i < locations.length; i++) {
var thisDistance = 0;
var start = origin;
var end = locations[i];
var request = {
origin: start,
destination: end,
travelMode: google.maps.DirectionsTravelMode.DRIVING
};
directionsService.route(request, function(response, status) {
if (status == google.maps.DirectionsStatus.OK) {
thisDistance = response.routes[0].legs[0].distance.value;
if (thisDistance < maxDistance) {
destn = response.routes[0].legs[0].end_address;
maxDistance = thisDistance;
}
} else {
document.getElementById(\"addressNotFound\").style.display = \'block\';
}
});
}
calcShortestRoute(origin, destn);
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// global count variable var callbackCount = 0; for (var i = 0; i<locations.length; i++) { var thisDistance=0; var start = origin; var end = locations[i]; var request = { origin:start, destination:end, travelMode: google.maps.DirectionsTravelMode.DRIVING }; directionsService.route(request, function(response, status) { if (status == google.maps.DirectionsStatus.OK) { thisDistance = response.routes[0].legs[0].distance.value; if (thisDistance < maxDistance) { destn = response.routes[0].legs[0].end_address; maxDistance = thisDistance; } } else { document.getElementById(\"addressNotFound\").style.display = \'block\'; } // move this to here, and pass in number of locations calcShortestRoute(origin, destn, locations.length); }); }function calcShortestRoute(origin, destn, locationCount) { // increment callback count callbackCount++; if (callbackCount == locationCount) { // all responses have returned // do your distance checking .... } }卧沫
... // your code var responseCount = 0; for (var i = 0; i < locations.length; i++) { ... // your code directionsService.route(request, function(response, status) { ... // your code if (++responseCount == locations.length) { calcShortestRoute(origin, destn); } }); }