javascript - 通过另一个预定义的数组元素作为键来重构 JavaScript 对象数组

Question

我也在 jsbin 上放置了相同的代码:https://jsbin.com/literefeqo/edit?js,console

说明

我有一个对象数组 (1)，并且想要转换(可能使用 map )该对象。转换标准是给定数组 (2)，对应于 arrObj 中的 german 属性。这意味着，如果 arrObj 中有一个 german 属性，则应将其“复制”出来，并应将其用作生成 resultObj (3) 的键。如果没有 german 属性，那么键应该是“未知”或其他。

注意:resultObj 中可以有更多条目，例如蒙塔格。这样 resultObj.Montag[i] 应该是一个对象数组。

(1) 对象数组

const arrObj = [
{
    "day": {
    "string": "Monday",
    "Number": 1
    },
    "description": {
    "type": "string",
    "value": "The first day of the week"
    },
    "german": {
    "type": "string",
    "value": "Montag"
    }
},
{
    "day": {
    "string": "Tuesday",
    "Number": 2
    },
    "description": {
    "type": "string",
    "value": "The second day of the week"
    }
},
{
    "day": {
    "string": "Wednesday",
    "Number": 3
    },
    "description": {
    "type": "string",
    "value": "The third day of the week"
    },
    "german": {
    "type": "string",
    "value": "Mittwoch"
    }
}
];

(2) 应该成为新对象的键的数组

const germanDays = ["Montag","Dienstag","Mittwoch","Donnerstag"];

(3) 结果应如下所示

const resultObj =   {
"Montag": [
  {
    "day": {
      "string": "Monday",
      "Number": 1
    },
    "description": {
      "type": "string",
      "value": "The first day of the week"
    },
    "german": {
      "type": "string",
      "value": "Montag"
    }
  }
],
"Dienstag": [
  {}
],
"Mittwoch": [
  {
    "day": {
      "string": "Wednesday",
      "Number": 3
    },
    "description": {
      "type": "string",
      "value": "The third day of the week"
    },
    "german": {
      "type": "string",
      "value": "Mittwoch"
    }
  }
],
"Donnerstag": [
  {}
],
"Unknown": [
  {
    "day": {
      "string": "Tuesday",
      "Number": 2
    },
    "description": {
      "type": "string",
      "value": "The second day of the week"
    }
  }
]

};

Answer 1

(possibly using map)

map，是数组到数组的映射，更合适的函数是reduce。

这是一个示例。

const germanDays = ["Montag","Dienstag","Mittwoch","Donnerstag"]

const arrObj = [
{
    "day": {
    "string": "Monday",
    "Number": 1
    },
    "description": {
    "type": "string",
    "value": "The first day of the week"
    },
    "german": {
    "type": "string",
    "value": "Montag"
    }
},
{
    "day": {
    "string": "Tuesday",
    "Number": 2
    },
    "description": {
    "type": "string",
    "value": "The second day of the week"
    }
},
{
    "day": {
    "string": "Wednesday",
    "Number": 3
    },
    "description": {
    "type": "string",
    "value": "The third day of the week"
    },
    "german": {
    "type": "string",
    "value": "Mittwoch"
    }
},
{
    "day": {
    "string": "Monday",
    "Number": 1
    },
    "description": {
    "type": "string",
    "value": "Just another text is here"
    },
    "german": {
    "type": "string",
    "value": "Montag"
    }
}
];

const ret = germanDays.reduce((a, v) => {
  const f = arrObj.filter(f => f.german && f.german.value === v);
  a[v] = f;
  return a;
}, {
  "Unknown": arrObj.filter(f => !f.german)
});


console.log(ret);