Question

我有一个java脚本函数返回一个字符串值，当我在按钮上调用此函数时单击它不返回任何内容。

这是我的功能代码：

function PlotMap(StartLat, StartLog, EndLat, EndLog) {

var map;
var directionsDisplay;
var directionsService = new google.maps.DirectionsService();
var llList = "";

function initMap() {

    map = new google.maps.Map(document.getElementById('map'), {
        center: { lat: StartLat, lng: StartLog },
        zoom: 15
    });


    directionsDisplay = new google.maps.DirectionsRenderer();
    directionsDisplay.setMap(map);
    calcRoute();

} //End function initMap


function calcRoute() {
    var start = new google.maps.LatLng(StartLat, StartLog);
    var end = new google.maps.LatLng(EndLat, EndLog);
    var bounds = new google.maps.LatLngBounds();

    bounds.extend(start);
    bounds.extend(end);
    map.fitBounds(bounds);

    var request = {
        origin: start,
        destination: end,
        travelMode: google.maps.TravelMode.DRIVING
    };

    directionsService.route(request, function (response, status) {
        if (status == google.maps.DirectionsStatus.OK) {
            directionsDisplay.setDirections(response);
            directionsDisplay.setMap(map);

            if (response.routes && response.routes.length > 0) {
                var routes = response.routes;
                for (var j = 0; j < routes.length; j++) {
                    var points = routes[j].overview_path;
                    var ul = document.getElementById("vertex");
                    for (var i = 0; i < points.length; i++) {
                        var li = document.createElement('li');
                        li.innerHTML = getLiText(points[i]);
                        ul.appendChild(li);
                        llList = llList + getLiText(points[i]) + " / ";
                    }
                }
            }
        } else {
            alert("Directions Request from " + start.toUrlValue(6) + " to " + end.toUrlValue(6) + " failed: " + status);
        }
    });
} //End function calcRoute

function getLiText(point) {
    var lat = point.lat(),
        lng = point.lng();
    return "lat: " + lat + " lng: " + lng;
}


initMap();

return llList;}

在这里，我在asp.net页面上点击按钮调用此功能。

<script>

function ii() {

    var tt = PlotMap(26.547648, 81.529472, 26.612515, 81.354248);

    alert(tt);
}</script>

Asp.net页面代码：

<body>
<input id="Button1" type="button" value="button" onclick="ii();"/>
<div id="map" style="float: left; width: 70%; height: 400px;"></div>
<ul id="vertex">
    <li></li>
</ul>

一切正常但功能不返回任何值。请帮助我成为网络开发的新手。感谢。

Answer 1

我测试了代码中的逻辑，看起来很合理。因为我能够让它返回你想要的刺痛但必须注释掉所有的谷歌地图逻辑。

虽然，我注意到，下面的if语句没有else语句，因此如果此语句返回false，则字符串将为空，并且您不会收到警报。

if (response.routes && response.routes.length > 0) {

也许尝试添加匹配的else语句：

} else { alert("No Routes"); }

这至少可以让你更深入地了解正在发生的事情。

以下是calcRoute函数中的新逻辑：

function calcRoute() {
    var start = new google.maps.LatLng(StartLat, StartLog);
    var end = new google.maps.LatLng(EndLat, EndLog);
    var bounds = new google.maps.LatLngBounds();

    bounds.extend(start);
    bounds.extend(end);
    map.fitBounds(bounds);

    var request = {
        origin: start,
        destination: end,
        travelMode: google.maps.TravelMode.DRIVING
    };

    directionsService.route(request, function (response, status) {
        if (status == google.maps.DirectionsStatus.OK) {
            directionsDisplay.setDirections(response);
            directionsDisplay.setMap(map);

            if (response.routes && response.routes.length > 0) {
                var routes = response.routes;
                for (var j = 0; j < routes.length; j++) {
                    var points = routes[j].overview_path;
                    var ul = document.getElementById("vertex");
                    for (var i = 0; i < points.length; i++) {
                        var li = document.createElement('li');
                        li.innerHTML = getLiText(points[i]);
                        ul.appendChild(li);
                        llList = llList + getLiText(points[i]) + " / ";
                    }
                }
            } else { alert("No Routes"); }
        } else {
            alert("Directions Request from " + start.toUrlValue(6) + " to " + end.toUrlValue(6) + " failed: " + status);
        }
    });
} //End function calcRoute

Java脚本函数不返回值

1 个答案: