如何将特定的对象元素从JSON数组转换为JavaScript数组

Question

I have an external JSON-file. It looks like this:

{
"type":"FeatureCollection",
"totalFeatures":1,
"features":
    [{ 
    "type":"Feature",
    "id":"asdf",
    "geometry":null,
    "properties":
        {
        "PARAM1":"19 16 11",
        "PARAM2":"31 22 11",
        "PARAM3":"12 10 7",
        }
    }],
"crs":null
}`

As I think " features " is an JSON-array and " properties " an object of this array. I stuck at trying to " push " the element " PARAM1 " into another array in my JS-code. My attempt was to get the data via jQuery AJAX. It looks like this:

function (){
var arrPARAM1 = new Array ();
$.ajax({
    async: false,
    url: 'gew.json',
    data: "",
    accepts:'application/json',
    dataType: 'json',
    success: function(data) {
        arrPARAM1.push(data.features);
    }
})
console.log(arrPARAM1);
}

With arrPARAM1.push(data.features) I can " push " the whole array " features " into my JS-array. But I only want to have the element " PARAM1 " from the object " properties ". How can I get deeper ( features --> properties --> PARAM1 )?

Thanks for your attention!

---

SOLUTION:

arrPARAM1.push(data.features[0].properties.PARAM1);

Answer 1

它只是一个具有单个元素的数组，因此访问[0]然后访问.properties

arrPARAM1.push(data.features[0].properties.PARAM1);

Answer 2

You would be looking for something like this:

data.features[0].properties["PARAM1"]

Or

data.features[0].properties.PARAM1

Answer 3

您将要素定义为数组，因此在访问要素时，必须将其视为数组。

arrPARAM1.push(data.features[0].properties.PARAM1); //gets param1 from the features array

Answer 4

In case you have multiple features:

data.features.forEach(function(feature) {
    arrPARAM1.push(feature.properties.PARAM1);
})