javascript - IF 条件下的 Google map

Question

我有一个场景，如果长纬度变为空，则谷歌地图会加载来自数据库的经度和纬度，或者使用也来自数据库的邮政编码。我将长、纬度、Pin 代码值绑定(bind)到隐藏字段。

脚本是:

var lat = $('#<%=hdnLat.ClientID %>').val();
var long = $('#<%=hdnLong.ClientID %>').val();
var add = $('#<%=hdnAddress.ClientID %>').val();
var title = $('#<%=hdnTitle.ClientID %>').val();
var pinCode = $('#<%=hdnPin.ClientID %>').val();

if (!lat == '' || !lat == null) {
    function initialize() {
        var latlng = new google.maps.LatLng(lat, long);
        var zoomratio = 15;
        var mapOptions = {
            center: latlng,
            zoom: zoomratio,
            scrollwheel: true,
            draggable: true,
            mapTypeControl: true,
            mapTypeControlOptions: {
                style: google.maps.MapTypeControlStyle.HORIZONTAL_BAR,
                position: google.maps.ControlPosition.RIGHT_TOP
            },
            panControl: false,
            zoomControl: true,
            streetViewControl: false,
            mapTypeId: google.maps.MapTypeId.ROADMAP,
            zoomControlOptions: {
                style: google.maps.ZoomControlStyle.SMALL,
                position: google.maps.ControlPosition.RIGHT_BOTTOM
            }
        };
        var infoWindow = new google.maps.InfoWindow();
        var map = new google.maps.Map(document.getElementById("googlemap"), mapOptions);
        var url = "Images/YellowPages/pointer.png";
        var htmlStr = "<div style='border:1px solid #ddd;padding:3px;'>" +
           "<h4 style='margin-top:0;width:200px;line-height:1.25;'>" + title + "</h4>" +
           "<p>" + add + "</p>" +
           "</div>";
        var marker = new google.maps.Marker({
            position: latlng,
            map: map,
            icon: url,
            title: title
        });
        (function (marker, htmlStr) {
            google.maps.event.addListener(marker, "click", function (e) {
                infoWindow.setContent(htmlStr);
                infoWindow.open(map, marker);
            });
        })(marker, htmlStr);
    }
    google.maps.event.addDomListener(window, 'load', initialize);
} else {
    function initialize() {
        geocoder = new google.maps.Geocoder();
        var latlng = new google.maps.LatLng(12.9539974, 77.6309395);
        var zoomratio = 8;
        var mapOptions = {
            center: latlng,
            zoom: zoomratio,
            scrollwheel: true,
            draggable: true,
            mapTypeControl: true,
            mapTypeControlOptions: {
                style: google.maps.MapTypeControlStyle.HORIZONTAL_BAR,
                position: google.maps.ControlPosition.RIGHT_BOTTOM
            },
            panControl: false,
            zoomControl: true,
            streetViewControl: false,
            mapTypeId: google.maps.MapTypeId.ROADMAP,
            zoomControlOptions: {
                style: google.maps.ZoomControlStyle.SMALL,
                position: google.maps.ControlPosition.RIGHT_BOTTOM
            }
        }
        map = new google.maps.Map(document.getElementById('googlemap'), mapOptions);
        codeAddress();
    }

    function codeAddress() {

        geocoder.geocode({ 'address': pinCode + ', India' }, function (results, status) {
            if (status == google.maps.GeocoderStatus.OK) {
                map.setCenter(results[0].geometry.location);
                var marker = new google.maps.Marker({
                    map: map,
                    position: results[0].geometry.location
                });
            } else {
                alert('Geocode was not successful for the following reason: ' + status);
            }
        });
    }
    google.maps.event.addDomListener(window, 'load', initialize);
}

问题是google.maps.event.addDomListener(window, 'load',initialize);总是首先设置为第一个条件，然后如果有值则立即跳转到第二个条件lat 和 long 变量。

有什么办法可以避免它或者有什么简单的方法吗？

Answer 1

您的情况有问题

if(!lat == '' || !lat == null)

始终评估为 TRUE(因为 !lat 表示 FALSE)

你想写的是:

if(lat != '' || lat != null)