Question

我正在尝试阅读一个简单的json数据文件。但我一直得到＆＃34; Uncaught TypeError：无法读取属性＆＃39; lat＆＃39;未定义＆＃34; 错误。我不确定为什么。我尝试过多次尝试更改json文件的结构，但无济于事。任何协助都会受到欢迎。

for (var i = 0; i < 1000; i++) {
    var dataCoal = data.coal[i];

    // Creating a random position
    var latLng = new google.maps.LatLng(dataCoal.lat,dataCoal.lon);


    //Uncaught TypeError: Cannot read property 'lat' of undefined


    // Creating a marker. Note that we don't add it to the map
    var marker = new google.maps.Marker({
      position: latLng
    });

    // Adding the marker to the markers array
    markers.push(marker);

  }

这是JSON文件中的一个条目

var data = { "coal": [{"NAME":"Haju Coal","Metals":"Coal","Lat":-0.11667,"Lon":114.85,"Accuracy":"approximate","DevStage":"Preproduction","ActStatus":"Temporarily On Hold","Company":"BHP Billiton Group","InSitu":700,"Metals_ft_style":0,"Accuracy_ft_style":0,"DevStage_ft_style":0,"ActStatus_ft_style":0}]}

Answer 1

你应该有一些东西来表示你的循环结束。

for (var i = 0; i < 1; i++) {

除此之外，您唯一有错误的是lat和lon小写

var latLng = new google.maps.LatLng(dataCoal.Lat,dataCoal.Lon);

应该做的伎俩

所以看起来应该是

var data = { "coal": [{"NAME":"Haju Coal","Metals":"Coal","Lat":-0.11667,"Lon":114.85,"Accuracy":"approximate","DevStage":"Preproduction","ActStatus":"Temporarily On Hold","Company":"BHP Billiton Group","InSitu":700,"Metals_ft_style":0,"Accuracy_ft_style":0,"DevStage_ft_style":0,"ActStatus_ft_style":0}]}
for (var i = 0; data.length < 1000; i++) {
    var dataCoal = data.coal[i];

    // Creating a random position
    var latLng = new google.maps.LatLng(dataCoal.Lat, dataCoal.Lon);

    //Uncaught TypeError: Cannot read property 'lat' of undefined


    // Creating a marker. Note that we don't add it to the map
    var marker = new google.maps.Marker({
      position: latLng
    });

    // Adding the marker to the markers array
    markers.push(marker);

}

Answer 2

我认为最好的方法是像PHP中的foreach一样迭代data.coal：

var coal;
for (var index in data.coal) {

  if (data.coal.hasOwnProperty(index)) {
    coal = data.coal[index];

    var latLng = new google.maps.LatLng(coal.Lat, coal.Lon);

    // ...

  }
}

读取.json文件，并收到错误

2 个答案: