javascript - 如何从 JSON 中获取包含 javascript 中重复项的计数？

Question

我有如下 JSON，

var json =
         [
            {"cardAid":"ALPHG","displayName":"ALPHG","SequenceNumber":"0","port":"A"},
            {"cardAid":"ALPHG","displayName":"ALPHG","SequenceNumber":"1","port":"B"},
            {"cardAid":"SFD","displayName":"SFD","SequenceNumber":"2","port":"C"},
            {"cardAid":"SFD","displayName":"SFD","SequenceNumber":"3","port":"D"},
            {"cardAid":"ALPHG","displayName":"ALPHG","SequenceNumber":"4","port":"E"},
            {"cardAid":"ALPHG","displayName":"ALPHG","SequenceNumber":"5","port":"F"},
            {"cardAid":"BETA","displayName":"BETA","SequenceNumber":"6","port":"G"}
        ];

我使用代码从这个链接解析这个 JSON， TO Get the number of Count from JSON in javascript?

function count(arr) {
    var map = {};
    for (var i = 0; i < arr.length; i++) {
        var name = arr[i].cardAid;
        var port = arr[i].port;
        if (name in map){
            map[name].Count++;
            map[name].Port += ',' + port;
        } else {
            map[name] = { Count: 1, Port: port };
        }
    }
    return map;
}

此函数使用 cardAid 作为键解析 JSON，并给出输出，

{
  ALPHG: { Count: 4, Port: "A,B,E,F" },
  SFD: { Count: 2, Port: "C,D" },
  BETA: { Count: 1, Port: "G" }
}

但我需要基于 JSON 中的 SequenceNumber 的输出，

{
  ALPHG: { Count: 2, Port: "A,B" },
  SFD: { Count: 2, Port: "C,D" },
  ALPHG: { Count: 2, Port: "E,F" },
  BETA: { Count: 1, Port: "G" }
}

我如何根据 JSON 中的 SequenceNumber 将这个重复名称放入 Map 中

Answer 1

这可能接近您的想法 ( jsfiddle )，我选择将 Port 作为数组而不是字符串。但我有点困惑，因为 SequenceNumber 在此逻辑中没有影响，也许元素应该首先按 SequenceNumber 排序？

function count(data) {
    var result = {};

    for (var i = 0; i < data.length; ++i) {
        var cardAid = data[i].cardAid;

        if (!(cardAid in result)) {
            result[cardAid] = [];
        }

        // Check if a new "sequence" needs to be created
        if (i == 0 || data[i-1].cardAid != cardAid) {
            result[cardAid].push({ Count: 0, Port: [] });
        }

        // Append item to the latest sequence
        var lastIndex = result[cardAid].length - 1;
        ++result[cardAid][lastIndex].Count;
        result[cardAid][lastIndex].Port.push(data[i].port);
    }

    return result;
}

结果:

{
  "ALPHG": [
    {
      "Count": 2,
      "Port": [ "A", "B" ]
    },
    {
      "Count": 2,
      "Port": [ "E", "F" ]
    }
  ],
  "SFD": [
    {
      "Count": 2,
      "Port": [ "C", "D" ]
    }
  ],
  "BETA": [
    {
      "Count": 1,
      "Port": [ "G" ]
    }
  ]
}