javascript - 这是对总结对象数组有益的 JavaScript 重构吗？

Question

这可能不是这里的典型问题，但我确实没有认识的人来检查这个问题。我正在对别人的代码进行一些重构，只是想听听第二个意见，因为我当然认为我的工作让它变得更好，但是来自你们专业人士的一些验证会很有帮助。 p>

从这样的数组开始:

errorLog: [{
 errorCode: 11,
 errorDescription: "abc",
 date: "2017-01-01",
 severity: "H"
},{
 errorCode: 11,
 errorDescription: "abcd",
 date: "2017-01-02",
 severity: "H"
},{
 errorCode: 99,
 errorDescription: "abcd",
 date: "2017-01-02",
 severity: "H"
}]

并尝试获得这样的结果:

errorSummary: [{
 errorCode: 11,
 severity: "H",
 count: 2
},{
 errorCode: 99,
 severity: "H",
 count: 1
}]

这是现有代码:

//instead of this, which is hard to reason about and debug (and includes a line that will never rturn true: if (hardErrorsSorted.includes...)):
let hardErrors = testData.filter(ts1 => ts1.severity === 'H');
let hardErrorsSorted = hardErrors.sort(this.mySorter);
for (let i = 0; i < hardErrorsSorted.length; i++) {
  if (i != hardErrorsSorted.length - 1) {
    if (hardErrorsSorted[i].errorCode != hardErrorsSorted[i + 1].errorCode) {
      let errorCount = this.getCount(hardErrorsSorted, hardErrorsSorted[i].errorCode);
      this.errorDataList.push({
        errorCode: hardErrorsSorted[i].errorCode,
        errorCodeType: 'H',
        errorCodeTotalCount: errorCount
      });
    }
  } else {
    if (hardErrorsSorted.includes(hardErrorsSorted[i].errorCode, 0)) {
    } else {
      let errorCount = this.getCount(hardErrorsSorted, hardErrorsSorted[i].errorCode);
      this.errorDataList.push({
        errorCode: hardErrorsSorted[i].errorCode,
        errorCodeType: 'H',
        errorCodeTotalCount: errorCount
      });
    }
  }
}

以及我的重构:

//use something like this, which is much easier to grasp at a glance, doesn't jump around, and is DRYer
let hardErrorCodes = testData.filter(ts => ts.severity === 'H').map(v => v.errorCode);
let hardErrorCounts = {};

//sum up the unique errors
for (let error of hardErrorCodes) {
  if (!(error in hardErrorCounts)) {
    hardErrorCounts[error] = 0;
  }
  hardErrorCounts[error]++;
}

//add the summed error counts to the master list
for (let error in hardErrorCounts) {
  this.errorDataList.push({
    errorCode: error, 
    errorCodeType: "H", 
    errorCodeTotalCount: hardErrorCounts[error]
  });

大家觉得怎么样？一个有用的重构？还是浪费时间？

Answer 1

你甚至可以更进一步:

const result = [], ids = {};

for(const {errorCode, severity} of hardErrorCodes){
  if(severity !== "H") continue;
  if(ids[errorCode]){
    ids[errorCode].count++;
  }else{
    result.push( ids[errorCode] = { severity, errorCode, count: 1});
  }
}

这使其速度提高了 3 倍(理论上)

如果您不想过滤严重性:

for(const {errorCode, severity} of hardErrorCodes){
  if(ids[severity + errorCode]){
    ids[severity + errorCode].count++;
  }else{
    result.push( ids[severity + errorCode] = { severity, errorCode, count: 1});
  }
}