Javascript：通过数组循环创建监听器，通过引用和值调用问题？ [英] Javascript: Looping through an array to create listeners, issue with call by reference and value?

问题描述

（var j = 0; j< layerData [i] .data.length; j ++）对于（var i = 0; i< layerCount; i ++）{
）的

  {
 var text = layerData [i] .data [j] .text; 
 var latlng = new google.maps.LatLng（layerData [i] .data [j] .lat，layerData [i] .data [j] .lng）; 
 var marker = new google.maps.Marker（{map：map，position：latlng}）; 
 var infowindow = new google.maps.InfoWindow（{content：text}）; 
 google.maps.event.addListener（marker，'click'，function（）{infowindow.open（map，marker）;}）; 
 
 
  

上面代码中的问题很可能在以 google.maps.event.addListener 开头。无论点击哪个标记，我都会获得一个infowindow，用于数据字段 layerdata [i] .data [j] 中的最后一项。好像我是通过引用调用而不是按值调用的，所以所有监听器的 infowindow 和标记是最后一项数组。

但我怎么能解决这个问题？

非常感谢！

解决方案

您必须创建一个封闭：（var i = 0; i< layerCount; i ++）{
for（var） j = 0; j var text = layerData [i] .data [j] .text;
var latlng = new google.maps.LatLng（layerData [i] .data [j] .lat，layerData [i] .data [j] .lng）;
var marker = new google.maps.Marker（{map：map，position：latlng}）;
var infowindow = new google.maps.InfoWindow（{content：text}）;

bindOpenWindow（infowindow，map，marker）;



函数bindOpenWindow（infowindow，map，marker）
{
google.maps.event.addListener（marker，'click'， function（）{infowindow.open（map，marker）;}）;
}

看看是否有帮助;）

for (var i=0; i<layerCount; i++){
    for (var j=0; j<layerData[i].data.length; j++){
        var text = layerData[i].data[j].text;
        var latlng = new google.maps.LatLng(layerData[i].data[j].lat, layerData[i].data[j].lng);
        var marker = new google.maps.Marker({map: map, position: latlng});
        var infowindow = new google.maps.InfoWindow({content: text});
        google.maps.event.addListener(marker, 'click', function() {infowindow.open(map,marker);});
    }
}

The problem in the above code most likely is in the line starting with google.maps.event.addListener. Whichever marker I click, I get a infowindow opening up for the last item in the data field of layerdata[i].data[j]. Seems like I am calling by reference and not by value, so infowindow and marker for all listeners are the last items in the arrays.

But how can I solve this?

many thanks!

解决方案

You have to create a closure:

for (var i=0; i<layerCount; i++){
    for (var j=0; j<layerData[i].data.length; j++){
        var text = layerData[i].data[j].text;
        var latlng = new google.maps.LatLng(layerData[i].data[j].lat, layerData[i].data[j].lng);
        var marker = new google.maps.Marker({map: map, position: latlng});
        var infowindow = new google.maps.InfoWindow({content: text});

        bindOpenWindow(infowindow, map, marker);
    }
}

function bindOpenWindow(infowindow, map, marker)
{
    google.maps.event.addListener(marker, 'click', function() {infowindow.open(map, marker);});
}

See if it helps ;)

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