js 数组,数据补全

var arr = [
    {datakey: "a", item: "28日19:27:33", scaleValue: "0"},
    {datakey: "b", item: "28日19:27:33", scaleValue: "1"},
    {datakey: "a", item: "28日19:28:00", scaleValue: "3"},
    {datakey: "b", item: "28日19:28:00", scaleValue: "1"},
    {datakey: "c", item: "28日19:28:00", scaleValue: "3"}
]

//补全后
{"a":["3","3"],"b":["1","1"],"c":[null,"0"]}

      let keyDataMap = {};
        let timeArr = [];

        function generateDataForEchar(dataArr) {
          let currentTimeData = {
            "timeStamp": "",
            "timeStampData": {}
          }
          for (let i = 0; i < dataArr.length; i++) {
            let data = dataArr[i];
            let timeStamp = data["item"];
            let timeStampData;
            if (!!currentTimeData.timeStamp && currentTimeData.timeStamp === timeStamp) {
              //表示当前的数据仍是同一个时间节点,就先缓存
              timeStampData = currentTimeData["timeStampData"];
            } else {
              //表示当前出现了一个新的时间点，此时需要将上一个时间点的数据存入各个数组中
              addDataToArr(currentTimeData);
              //重置时间节点的数据
              timeStampData = {}
              currentTimeData = {
                "timeStamp": timeStamp,
                timeStampData: timeStampData
              }
            }
            //对于同个时间点的同个key的逻辑，目前是取最后一次出现的，你可以根据实际需要进行调整
            timeStampData[data.datakey] = data.scaleValue;
          }
          //避免丢失最后一个时间点节点的数据
          addDataToArr(currentTimeData);
        }

        function addDataToArr(currentTimeData) {
          let timeStamp = currentTimeData.timeStamp;
          if (!!timeStamp) {
            timeArr.push(timeStamp);
            let timeStampData = currentTimeData.timeStampData;
            let tmpKeyMap = {};
            for (let dataKey in timeStampData) {
              let dataArr = keyDataMap[dataKey];
              let timeStampValue = timeStampData[dataKey];
              tmpKeyMap[dataKey] = "1";
              if (!dataArr) {
                dataArr = getArrayWithNull(timeArr.length - 1);
                keyDataMap[dataKey] = dataArr;
              }
              keyDataMap[dataKey].push(timeStampValue)
            }
            for (let dataKey in keyDataMap) {
              if (!tmpKeyMap[dataKey]) {
                //当前节点内未出现对应的dataKey,则对应节点加入一个null
                keyDataMap[dataKey].push(null);
              }
            }
          }
        }

        function getArrayWithNull(size) {
          let arr = []
          for (let i = 0; i < size; i++) {
            arr.push(null);
          }
          return arr;
        }

        generateDataForEchar(arr);
        console.log(timeArr);
        console.log(JSON.stringify(keyDataMap));

var arr = [
    {datakey: "a", item: "28日19:27:33", scaleValue: "0"},
    {datakey: "b", item: "28日19:27:33", scaleValue: "1"},
    {datakey: "a", item: "28日19:28:00", scaleValue: "3"},
    {datakey: "b", item: "28日19:28:00", scaleValue: "1"},
    {datakey: "c", item: "28日19:28:00", scaleValue: "3"}
]

// 补全后
  [
    {datakey: "a", item: "28日19:27:33", scaleValue: "0"},
    {datakey: "b", item: "28日19:27:33", scaleValue: "1"},
    {datakey: "c", item: "28日19:27:33", scaleValue: null},
    {datakey: "a", item: "28日19:28:00", scaleValue: "3"},
    {datakey: "b", item: "28日19:28:00", scaleValue: "1"},
    {datakey: "c", item: "28日19:28:00", scaleValue: "3"}
]

       //提取 datakey
        var keys = []
        arr.forEach(e => {
          keys.push(e.datakey)
        });
        keys = new Set(keys);

        //这部分是提取 同时间数据
        var resData = arr;
        let tempArr = [];
        let Data = [];
        for (let i = 0; i < resData.length; i++) {
          if (tempArr.indexOf(resData[i].item) === -1) {
            Data.push({
              item: resData[i].item,
              dataInfo: [resData[i]]
            });
            tempArr.push(resData[i].item);
          } else {
            for (let j = 0; j < Data.length; j++) {
              if (Data[j].item == resData[i].item) {
                Data[j].dataInfo.push(resData[i]);
                break;
              }
            }
          }
        }

        //这部分是补齐
        Data.forEach((e, i) => {
          if (e.dataInfo.length !== keys.length) {
            keys.forEach(sd => {
              if (findIndexByKeyValue(e.dataInfo, 'datakey', sd) != -1) {
                // console.log('yes', sd)
              } else {
                // console.log('no', sd);
                var obj = {
                  datakey: sd,
                  item: e.dataInfo[0].item,
                  scaleValue: null
                }
                e.dataInfo.push(obj)
              }
            });
          }
        });
      //  console.log('补齐', Data)
      
        function findIndexByKeyValue(arr, key, valuetosearch) {
          for (var i = 0; i < arr.length; i++) {
            if (arr[i][key] == valuetosearch) {
              return i;
            }
          }
          return -1;
        }
        //提取, 压平
        var arrN = []
        Data.forEach(e => {
          // console.log('eeee', e.dataInfo)
          arrN.push(e.dataInfo)
        });
        arrN = arrN.flat()
        console.log('最终', arrN)

最后

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