Javascript Google Maps v3 中的“marker.setVisible(false)”和“marker.setMap(null)”有什么区别？
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What is the difference between "marker.setVisible(false)" and "marker.setMap(null)" in Google Maps v3?
提问by zjm1126
I want to clear a marker on Google Maps.
我想清除 Google 地图上的标记。
What is the difference between marker.setVisible(false)and marker.setMap(null)?
marker.setVisible(false)和 和有marker.setMap(null)什么区别？
But I don't know, which is right?
但我不知道，哪个是对的？
回答by Daniel Vassallo
The difference between the two methods does not seem to be clearly documented. However, note the following:
这两种方法之间的区别似乎没有明确记录。但是，请注意以下几点：
When you use
setMap(null), your marker will lose the reference to theMap. If you do not keep a reference to theMapobject, you wouldn't be able to reshow the marker.In addition, the
setMap()method will not trigger thevisible_changedevent, while thesetVisible()method does (if the visibility is actually toggled).
当您使用 时
setMap(null)，您的标记将丢失对 的引用Map。如果您不保留对Map对象的引用，您将无法重新显示标记。此外，该
setMap()方法不会触发visible_changed事件，而该方法会触发setVisible()（如果可见性实际上已切换）。
Example:
例子：
var map = new google.maps.Map(document.getElementById('map'), {
zoom: 4,
center: new google.maps.LatLng(-25.363, 131.044),
mapTypeId: google.maps.MapTypeId.ROADMAP
});
var marker = new google.maps.Marker({
position: new google.maps.LatLng(-25.363, 131.044),
map: map
});
google.maps.event.addListener(marker, 'visible_changed', function() {
console.log('visible_changed triggered');
});
marker.setVisible(false); // visible_changed triggered
marker.setVisible(true); // visible_changed triggered
marker.setMap(null); // visible_changed not triggered
marker.setMap(map); // visible_changed not triggered
I guess we should be using the setVisible(false)method when we intend to reshow the marker again on the map, and the setMap(null)when we will not be showing it again.
我setVisible(false)想当我们打算在地图上再次重新显示标记时，我们应该使用该方法，而setMap(null)当我们不会再次显示它时。
回答by Phil Glau
Another key distinction is that setMap(NULL)releases the resources associated with the marker whereas setVisible(false)just makes the marker invisible, but the resources associated with the marker are still allocated.
另一个关键区别是setMap(NULL)释放与标记关联的资源，而setVisible(false)只是使标记不可见，但与标记关联的资源仍然被分配。
If you're dealing with 100s or 1000s of markers, this can become a significant performance and memory issue.
如果您正在处理 100 或 1000 个标记，这可能会成为一个重要的性能和内存问题。
