Javascript传递参数给回调函数或在DistanceMatrixStatus中设置变量值

Question

我已经开始尝试使用Google的DistanceMatrixService，下面的代码可以工作，但是我如何传递另一个参数给回调函数，或者从回调函数中取出一个值呢？

例如：我有两个div（Results1和Results2），我想在其中展示不同的结果，所以我认为我需要
要么向GoogleMapDistance函数传递另一个值，例如GoogleMapDistance(YourLatLong,DestLatLong,TheDiv)
要么
能够从回调函数外部获取ResultStr的值：document.getElementById("Results1").innerHTML = ResultStr;
要么
将innerHTM设置为函数的返回值 document.getElementById("Results1").innerHTML = GoogleMapDistance(YourLatLong,DestLatLong);

我卡住了。我该怎么办才能实现这个功能呢？目前看来，我只能运行所有这些代码一次，并且只写入一个div。

<div id="Results1"></div>
<div id="Results2"></div>

<script src="https://maps.googleapis.com/maps/api/js?v=3.exp&sensor=false"></script>
<script>

function GoogleMapDistance(YourLatLong,DestLatLong)
{
    var service = new google.maps.DistanceMatrixService();
    service.getDistanceMatrix(
    {
    origins: [YourLatLong],
    destinations: [DestLatLong],
    travelMode: google.maps.TravelMode.DRIVING,
    unitSystem: google.maps.UnitSystem.IMPERIAL,
    avoidHighways: false,
    avoidTolls: false
    }, callback);
}

function callback(response, status)
{
    if (status == google.maps.DistanceMatrixStatus.OK)
    {
    var origins = response.originAddresses;
    var destinations = response.destinationAddresses;
      for (var i = 0; i < origins.length; i++)
      {
          var results = response.rows[i].elements;
          for (var j = 0; j < results.length; j++)
          {
              var element = results[j];
              var from = origins[i];
              var to = destinations[j];
              var distance = element.distance.text;
              var duration = element.duration.text;
              var ResultStr = distance + "&nbsp; (<i>" + duration + "</i>)";
          }
      }
    document.getElementById("Results1").innerHTML = ResultStr;
    }
}

var YourLatLong = "45.4049,-122.797997";
var DestLatLong1 = "47.468893,-122.227978";
var DestLatLong2 = "61.221274,-149.831545";

GoogleMapDistance(YourLatLong,DestLatLong1);

</script>

- Soren

Answer 1

你无法更改Google如何调用回调函数，但你可以让它将你的本地函数作为回调函数进行调用，然后通过闭包再调用另一个回调函数并添加所需的额外参数，如下所示：

function GoogleMapDistance(YourLatLong,DestLatLong, item)
{
    var service = new google.maps.DistanceMatrixService();
    service.getDistanceMatrix(
    {
    origins: [YourLatLong],
    destinations: [DestLatLong],
    travelMode: google.maps.TravelMode.DRIVING,
    unitSystem: google.maps.UnitSystem.IMPERIAL,
    avoidHighways: false,
    avoidTolls: false
    }, function(response, status) {callback(response, status, item)});
}

或者，您可以直接在内联中定义回调函数，以便它可以直接访问父函数变量：

function GoogleMapDistance(YourLatLong,DestLatLong, item)
{
    var service = new google.maps.DistanceMatrixService();
    service.getDistanceMatrix(
    {
    origins: [YourLatLong],
    destinations: [DestLatLong],
    travelMode: google.maps.TravelMode.DRIVING,
    unitSystem: google.maps.UnitSystem.IMPERIAL,
    avoidHighways: false,
    avoidTolls: false
    }, function callback(response, status)
    {
        // you can access the parent scope arguments like item here
        if (status == google.maps.DistanceMatrixStatus.OK)
        {
        var origins = response.originAddresses;
        var destinations = response.destinationAddresses;
          for (var i = 0; i < origins.length; i++)
          {
              var results = response.rows[i].elements;
              for (var j = 0; j < results.length; j++)
              {
                  var element = results[j];
                  var from = origins[i];
                  var to = destinations[j];
                  var distance = element.distance.text;
                  var duration = element.duration.text;
                  var ResultStr = distance + "&nbsp; (<i>" + duration + "</i>)";
              }
          }
        document.getElementById("Results1").innerHTML = ResultStr;
        }
    }

)}

- jfriend00

---

如果我没有误解你的第一个选择，在这个 callback(response, status, item) 的主体中，又会调用另一个回调函数 item(some_arg)，是这样吗？ - SASM