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JavaScript变量为空[重复]

google-directions-api google-maps-api-3 javascript

-1

Philipp Rosengart · 技术社区 · 9 年前

我想使用“start”作为全局变量作为起点。所以我将其声明为全局变量,然后在CodeAddress函数中设置一个值。该值用于设置标记,该标记按预期工作。当我想在calcRoute函数中使用start变量时,它是未定义的。

我使用以下代码:

<script>
            var map;
            var uluru;
            var start; <-- Declaration
            var geocoder;

            function codeAddress() {
                var address = "Essen";
                geocoder = new google.maps.Geocoder();
                geocoder.geocode({
                    'address': address
                }, function(results, status) {
                    if (status == 'OK') {

                        start = results[0].geometry.location; <-- Setting value
                        
                        var marker = new google.maps.Marker({

                            position: start,
                            map: map
                        }); <-- Position is set, start has a value
                    } else {
                        alert('Geocode was not successful for the following reason: ' + status);
                    }
                });

                calcRoute();
            }

            function calcRoute() {
                var directionsService = new google.maps.DirectionsService;
                var directionsDisplay = new google.maps.DirectionsRenderer({map: map});
                directionsService.route({
                    origin: start, <-- start is undefined
                    destination: uluru,
                    travelMode: 'DRIVING'
                }, function(response, status) {
                    if (status === 'OK') {
                        directionsDisplay.setDirections(response);
                    } else {
                        window.alert('Directions request failed due to ' + status);
                    }
                });
            }

        </script>

1 回复 | 直到 9 年前

1

2

maazadeeb 9 年前

你需要打电话 calcRoute 一旦 start 开始 在回调中设置为 geocode 卡尔克劳特 在回调中,post设置 开始 .类似于

geocoder.geocode({address: address}, function(results, status) {
  if (status == 'OK') {  
    start = results[0].geometry.location;
    // do the rest
    calcRoute();
  }
});