javascript - 通过点表示法访问 JavaScript 对象

Question

我有一个具有该结构的 JavaScript 对象

myJsObject= {
    "type": "FeatureCollection",
    "features": [{
        "type": "Feature",
        "geometry": {
            "type": "Point",
            "coordinates": [84.1, 99.1]
        },
        "properties": {
            "value": "20",
            "s": "abc"
        }
    }, {
        "type": "Feature",
        "geometry": {
            "type": "Point",
            "coordinates": [18.15, 9.73]
        },
        "properties": {
            "value": "0",
            "s": "def"
        }
    }, {
        "type": "Feature",
        "geometry": {
            "type": "Point",
            "coordinates": [1.15, 4.78]
        },
        "properties": {
            "value": "10",
            "s": "fdg"
        }
    }, {
        "type": "Feature",
        "geometry": {
            "type": "Point",
            "coordinates": [17.15, 5.13]
        },
        "properties": {
            "value": "5",
            "s": "dfs"
        }
    }]
}

我尝试以这种方式访问​​它:

myJsObject.features.forEach(function(d) {
    d.LatLng = new L.LatLng(d.geometry.coordinates[1],
        d.geometry.coordinates[0]);
});

这让我返回未定义。我可以像这样访问

myJsObject.features;

像这样

myJsObject.features[0];

但不是这样的

myJsObject.features.geometry;

这是为什么呢？我需要后者用于 fr forEach 循环...

Answer 1

Why is that?

myJson.features 的值是一个数组。

它不是一个具有名为 geometry 属性的对象。

数组包含具有名为geometry属性的对象。