JSON 匹配键/值并获取每个键的总值答案

【问题标题】：JSON to match key/values and get the total values for each keyJSON 匹配键/值并获取每个键的总值
【发布时间】：2021-08-11 10:04:55
【问题描述】：

我需要帮助从我创建的 api 中显示每个目标名称的总会话时间。我已经尝试过映射和减少，但只能获得总 sessionTime。

我希望结果是这样的：
学习意大利语：6
Parla con il mio amico in Italiano : 1

"records": [
    {
      "sessionTime": 1,
      "goalName": "Learn Italian",
      "timeStapmed": "10:08:23",
      "date": "11/08/2021",
      "id": 1
    },
    {
      "sessionTime": 5,
      "goalName": "Learn Italian",
      "id": "PFKFKZ",
      "timeStapmed": "10:14:48",
      "date": "11/08/2021"
    },
    {
      "sessionTime": 1,
      "goalName": "Parla con il mio amico in italiano",
      "id": "aP_g1-",
      "timeStapmed": "10:21:28",
      "date": "11/08/2021"
    }
  ]

【问题讨论】：

标签： javascript arrays json mapreduce

【解决方案1】：

我认为您正在寻找 array#reduce 循环，

records.reduce(
  (acc, { sessionTime, goalName }) =>
    acc?.[goalName]
      ? { ...acc, [goalName]: acc[goalName] + sessionTime }
      : { ...acc, [goalName]: sessionTime },
  {}
);

我们可以遍历每个对象并将它们的值的总和保存在 acc 变量中。

完整代码：

let records = [
  {
    sessionTime: 1,
    goalName: "Learn Italian",
    timeStapmed: "10:08:23",
    date: "11/08/2021",
    id: 1,
  },
  {
    sessionTime: 5,
    goalName: "Learn Italian",
    id: "PFKFKZ",
    timeStapmed: "10:14:48",
    date: "11/08/2021",
  },
  {
    sessionTime: 1,
    goalName: "Parla con il mio amico in italiano",
    id: "aP_g1-",
    timeStapmed: "10:21:28",
    date: "11/08/2021",
  },
];


let newRecords = records.reduce((acc, {sessionTime, goalName}) => acc?.[goalName] ? {...acc, [goalName]: acc[goalName] + sessionTime} : {...acc, [goalName]: sessionTime}, {})

console.log(newRecords)

【讨论】：

【解决方案2】：

先尝试filter你要计算它们总和的元素。

const learnItalianTotal = records.filter(elm => elm.goalName === "Learn Italian")
.reduce((acc, cur) => acc.sessionTime + cur.sessionTime);

【讨论】：

【解决方案3】：

试试这个

const records = [
    {
        sessionTime: 1,
        goalName: 'Learn Italian',
        timeStapmed: '10:08:23',
        date: '11/08/2021',
        id: 1
    },
    {
        sessionTime: 5,
        goalName: 'Learn Italian',
        id: 'PFKFKZ',
        timeStapmed: '10:14:48',
        date: '11/08/2021'
    },
    {
        sessionTime: 1,
        goalName: 'Parla con il mio amico in italiano',
        id: 'aP_g1-',
        timeStapmed: '10:21:28',
        date: '11/08/2021'
    }
];


var result = records.reduce( ( accumulator, { sessionTime, goalName} ) => {
    accumulator[goalName] = accumulator[ goalName ] ? (accumulator[goalName] + sessionTime): sessionTime;
    return accumulator;
}, {} );

console.log(result);

输出

{
    "Learn Italian": 6,
    "Parla con il mio amico in italiano": 1
}

【讨论】：