如何通过比较数组（日期）和对象数组来生成 json？答案

【问题标题】：How to generate json by comparing both array(date) and array of objects?如何通过比较数组（日期）和对象数组来生成 json？
【发布时间】：2018-08-01 08:56:51
【问题描述】：

我想比较 node.js 中的数组和对象数组，并根据比较生成一个新的 json 对象。在下面的代码中，我有 "dateList" 日期列表和 result 有 json 数组，现在我想比较 dateList 和结果，如果结果对象有日期dateList 的值，然后我们必须获取执行值并推送到新数组中，如果不相等则我们必须推送为 0。

服务器代码：

var dateList = [
  "2018-08-01",
  "2018-07-31",
  "2018-07-30",
  "2018-07-29",
  "2018-07-28",
  "2018-07-27",
  "2018-07-26"
]
var result = [{
    CDate: '2018-07-31',
    executions: 1
  },
  {
    CDate: '2018-07-30',
    executions: 2
  },
  {
    CDate: '2018-07-27',
    executions: 3
  },
  {
    CDate: '2018-07-26',
    executions: 2
  }
];
var allList = [];

for (key in dateList) {
  for (keyResult in result) {
    if (dateList[key] === result[keyResult].CDate) {
      var obj = {
        "date": dateList[key],
        "value": result[keyResult].executions
      }
      allList.push(obj);
      break;
    } else {
      var obj = {
        "date": dateList[key],
        "value": 0
      }
      allList.push(obj)
      break;

    }
  }

}
console.log(allList);

电流输出：

[{
    "date": "2018-08-01",
    "value": 0
  },
  {
    "date": "2018-07-31",
    "value": 1
  },
  {
    "date": "2018-07-30",
    "value": 0
  },
  {
    "date": "2018-07-29",
    "value": 0
  },
  {
    "date": "2018-07-28",
    "value": 0
  },
  {
    "date": "2018-07-27",
    "value": 0
  },
  {
    "date": "2018-07-26",
    "value": 0
  }
]

预期输出：

[{
    "date": "2018-08-01",
    "value": 0
  },
  {
    "date": "2018-07-31",
    "value": 1
  },
  {
    "date": "2018-07-30",
    "value": 2
  },
  {
    "date": "2018-07-29",
    "value": 0
  },
  {
    "date": "2018-07-28",
    "value": 0
  },
  {
    "date": "2018-07-27",
    "value": 3
  },
  {
    "date": "2018-07-26",
    "value": 2
  }
]

请帮忙

【问题讨论】：

标签： arrays json date for-loop

【解决方案1】：

else 分支位于内部数组中，但是只有当内部循环没有在result 中找到给定日期时，您才想推送0-entry，您只知道循环结束的时间（新变量found 跟踪它）：

var dateList = [
  "2018-08-01",
  "2018-07-31",
  "2018-07-30",
  "2018-07-29",
  "2018-07-28",
  "2018-07-27",
  "2018-07-26"
]
var result = [{
    CDate: '2018-07-31',
    executions: 1
  },
  {
    CDate: '2018-07-30',
    executions: 2
  },
  {
    CDate: '2018-07-27',
    executions: 3
  },
  {
    CDate: '2018-07-26',
    executions: 2
  }
];
var allList = [];

for (key in dateList) {
  var found=false;
  for (keyResult in result) {
    if (dateList[key] === result[keyResult].CDate) {
      var obj = {
        "date": dateList[key],
        "value": result[keyResult].executions
      }
      allList.push(obj);
      found=true;
      break;
    }// else {
  }
  if(!found){
    var obj = {
      "date": dateList[key],
      "value": 0
    }
    allList.push(obj)
    //break;
  }
}
console.log(allList);

另一种方法是在开头创建一个0-entry，然后从内部循环更新它并在最后推送：

var dateList = [
  "2018-08-01",
  "2018-07-31",
  "2018-07-30",
  "2018-07-29",
  "2018-07-28",
  "2018-07-27",
  "2018-07-26"
]
var result = [{
    CDate: '2018-07-31',
    executions: 1
  },
  {
    CDate: '2018-07-30',
    executions: 2
  },
  {
    CDate: '2018-07-27',
    executions: 3
  },
  {
    CDate: '2018-07-26',
    executions: 2
  }
];
var allList = [];

for (key in dateList) {
  var obj = {
    "date": dateList[key],
    "value": 0
  };
  for (keyResult in result) {
    if (dateList[key] === result[keyResult].CDate) {
      obj.value=result[keyResult].executions;
      break;
    }
  }
  allList.push(obj)
}
console.log(allList)

【讨论】：

以上两种方法工作正常，第二种方法逻辑非常好。谢谢。:)