javascript - 操纵 JavaScript 数组

Question

我希望你能帮助我。如何转换这个扁平的 JavaScript 数组，来自:

[    {"state":"First State","district":"First District","local_district_id":1,"zone_id":117,"center_id":"A","center_name":"Voting Center First"},    {"state":"First State","district":"First District","local_district_id":2,"zone_id":117,"center_id":"B","center_name":"Voting Center Second"},    {"state":"First State","district":"First District","local_district_id":6,"zone_id":117,"center_id":"C","center_name":"Voting Center Third"},]

进入嵌套数组，像这样:

[{    "state": "First State",    "children": [{        "district_name": "First District",        "children": [{            "local_district_id": 1,            "zone_id": 117,            "center_id": "A",            "center_name": "Voting Center Name First",        }, {            "local_district_id": 2,            "zone_id": 117,            "center_id": "B",            "center_name": "Voting Center Name Second",        }, {            "local_district_id": 6,            "zone_id": 117,            "center_id": "C",            "center_name": "Voting Center Name Third",        }]    }]}]

Answer 1

你可以做这样的事情来让它在一个循环中工作。这不是最漂亮的功能，但它可以在没有大量额外开销的情况下完成工作。

<script>
var original = [
    {"state":"First State","district":"First District","local_district_id":1,"zone_id":117,"center_id":"A","center_name":"Voting Center First"},
    {"state":"Second State","district":"First District","local_district_id":2,"zone_id":117,"center_id":"B","center_name":"Voting Center Second"},
    {"state":"First State","district":"First District","local_district_id":6,"zone_id":117,"center_id":"C","center_name":"Voting Center Third"},
];

var statesUsed = {};
var districtsUsed = {};
var newArray = [];
var stateIndex = 0;
var districtIndex = 0;

for (var i=0,l=original.length;i<l;i++) {
    var state = original[i].state;
    var district = original[i].district;
    var local_district_id = original[i].local_district_id;
    var zone_id = original[i].zone_id;
    var center_id = original[i].center_id;
    var center_name = original[i].center_name;

    if (statesUsed[state] == undefined) {
        statesUsed[state] = stateIndex;
        stateIndex++;
        newArray.push({state : state, children : []});
    }

    districtsUsed[state] = (districtsUsed[state] == undefined) ? {} : districtsUsed[state];

    if (districtsUsed[state][district] == undefined) {
        newArray[statesUsed[state]].children.push({district_name : district, children : []});
        districtsUsed[state][district] = newArray[statesUsed[state]].children.length - 1;
    }

    newArray[statesUsed[state]].children[districtsUsed[state][district]].children.push({
          local_district_id : local_district_id,
          zone_id : zone_id,
          center_id : center_id,
          center_name : center_name
    });


}
</script>