Google Maps API指南：添加多个随机标注 博客分类： 个人杂谈 Google Maps API
程序员文章站
2024-03-08 12:04:34
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在执行事件侦听器时，通常可取的做法是将私有数据和持久性数据附加到对象中。JavaScript 不支持“私有”实例数据，但它支持允许内部函数访问外部变量的闭包。在事件侦听器访问通常不附加到发生事件的对象的变量时，闭包非常有用。
下例在事件侦听器中使用函数闭包将加密消息分配给一组标记。点击每个标记都可以看到加密消息的一部分，该消息并未包含在标记自身内。
下例在事件侦听器中使用函数闭包将加密消息分配给一组标记。点击每个标记都可以看到加密消息的一部分，该消息并未包含在标记自身内。
<!DOCTYPE html>
<html>
<head>
<meta name="viewport" content="initial-scale=1.0, user-scalable=no" />
<style type="text/css">
html { height: 100% }
body { height: 100%; margin: 0px; padding: 0px }
#map_canvas { height: 100% }
</style>
<script type="text/javascript"
src="https://maps.google.com/maps/api/js?sensor=false">
</script>
<script>
var map;
function initialize() {
var myLatlng = new google.maps.LatLng(22.279566,113.540955);
var myOptions = {
zoom: 14,
center: myLatlng,
mapTypeId: google.maps.MapTypeId.ROADMAP
}
map = new google.maps.Map(document.getElementById("map_canvas"), myOptions);
// Add 5 markers to the map at random locations
var southWest = new google.maps.LatLng(20.279566,112.540955);
var northEast = new google.maps.LatLng(22.279566,113.540955);
var bounds = new google.maps.LatLngBounds(southWest,northEast);
map.fitBounds(bounds);
var lngSpan = northEast.lng() - southWest.lng();
var latSpan = northEast.lat() - southWest.lat();
for (var i = 0; i < 5; i++) {
var location = new google.maps.LatLng(southWest.lat() + latSpan * Math.random(),
southWest.lng() + lngSpan * Math.random());
var marker = new google.maps.Marker({
position: location,
map: map
});
var j = i + 1;
marker.setTitle(j.toString());
attachSecretMessage(marker, i);
}
}
// The five markers show a secret message when clicked
// but that message is not within the marker's instance data
function attachSecretMessage(marker, number) {
var message = ["This","is","the","secret","message"];
var infowindow = new google.maps.InfoWindow(
{ content: message[number],
size: new google.maps.Size(50,50)
});
google.maps.event.addListener(marker, 'click', function() {
infowindow.open(map,marker);
});
}
</script>
</head>
<body onload="initialize()">
<div id="map_canvas" style="width:100%; height:100%"></div>
</body>
</html>