javascript - 如何正确使用 computeDistanceBetween()？

Question

我是 Maps API 的新手，我正在尝试从 2 个地址获取距离(以公里为单位)。这段代码有什么问题？

var mygc = new google.maps.Geocoder();

var locationOrigem;
var locationDestino;

var latOrigem  = 0;
var longOrigem = 0;

var latDestino  = 0;
var longDestino = 0;


mygc.geocode({'address' : 'Presidente Vargas 897, Centro RJ'}, function(results, status){

    locationOrigem = results[0].geometry.location;
    latOrigem   = results[0].geometry.location.lat();
    longOrigem  = results[0].geometry.location.lng();

});

mygc.geocode({'address' : 'Abelardo Bueno 3000, Barra da Tijuca RJ'}, function(results, status){

    locationDestino = results[0].geometry.location;
    latDestino  = results[0].geometry.location.lat();
    longDestino = results[0].geometry.location.lng();

});

alert(google.maps.geometry.spherical.computeDistanceBetween(locationOrigem, locationDestino));

由于未知原因，var locationOrigem 和 locationDestino 在匿名函数之外是“未定义的”？？？为什么？？？

Answer 1

你有没有包含这个脚本？

<script type="text/javascript" src="http://maps.google.com/maps/api/js?libraries=geometry&sensor=false&language=en"></script>

运行代码时会发生什么？您确定您的地址已正确进行地理编码吗？您确定问题出在 computeDistanceBetween 中吗？尝试转储所有变量。

更新:

对地理编码器的请求是异步执行的。因此，在您获得地理编码数据之前运行了距离计算请求。这就是您的变量未定义 的原因。您需要使用回调来确保请求已完成。试试这段代码

var mygc = new google.maps.Geocoder();
var locationOrigem;
var locationDestino;
var latOrigem  = 0;
var longOrigem = 0;
var latDestino  = 0;
var longDestino = 0;

mygc.geocode({'address' : 'Presidente Vargas 897, Centro RJ'}, function(results, status){
    locationOrigem = results[0].geometry.location;
    latOrigem   = results[0].geometry.location.lat();
    longOrigem  = results[0].geometry.location.lng();
    mygc.geocode({'address' : 'Abelardo Bueno 3000, Barra da Tijuca RJ'}, function(results, status){
        locationDestino = results[0].geometry.location;
        latDestino  = results[0].geometry.location.lat();
        longDestino = results[0].geometry.location.lng();
        console.log(locationOrigem);
        console.log(locationDestino);
        console.log(google.maps.geometry.spherical.computeDistanceBetween(locationOrigem, locationDestino));
    });
});

您还需要检查响应状态。我没有包括因为它不是主题。