多个 for 循环问题

Question

我有两个数组键和子Grps。使用这两个创建具有映射键到子Grps数组的新数组。var keys = ["Subgroup", "0-3", "3-10", "11-40"];var subGrps = ["SP_20k", "SP_40k", "SP_60k"];var arrayOfObjects = [];subGrps.forEach(function(id) {  keys.forEach(function(item) {    if (item === "Subgroup") {      arrayOfObjects.push({        [item]: id      });    } else {      arrayOfObjects.push({        [item]: ""      });    }  });});console.log(arrayOfObjects);预期输出：  [{    "Subgroup" : "SP_20k",    "0-3": "",    "3-10": "",    "11-40": ""  },  {    "Subgroup" : "SP_40k",    "0-3": "",    "3-10": "",    "11-40": ""  },  {    "Subgroup" : "SP_60k",    "0-3": "",    "3-10": "",    "11-40": ""  }]forEach是好的选择吗？用于对 对象进行分组，并获取该输出。我错过了什么来获得预期输出？有人可以帮我吗？keys arraysubGrps array

Answer 1

您可以使用 Array.map 循环访问数组，创建一个将键设置为 from 值的对象，并使用 Object.assign 为数组中的其他条目添加空值：subGrpsSubgroupsubGrpskeys




var keys = ["Subgroup", "0-3", "3-10", "11-40"];

var subGrps = ["SP_20k", "SP_40k", "SP_60k"];

var arrayOfObjects = subGrps.map(v => Object.assign({

    "Subgroup": v

  },

  ...keys.slice(1).map(k => ({

    [k]: ""

  }))

));

console.log(arrayOfObjects);

展开代码段

这可以简化为：

var keys = ["Subgroup", "0-3", "3-10", "11-40"];

var subGrps = ["SP_20k", "SP_40k", "SP_60k"];

var arrayOfObjects = subGrps.map(v => Object.assign({},

  ...keys.map(k => ({

    [k]: k == 'Subgroup' ? v : ""

  }))

));

console.log(arrayOfObjects);

Answer 2

您可以先创建对象，然后在循环中添加键。

var keys = ["Subgroup", "0-3", "3-10", "11-40"];

var subGrps = ["SP_20k", "SP_40k", "SP_60k"];

// creates the object with keys once

// you can also use foreach to create this keysObj too.

var keysObj = keys.reduce((resObj, acc) => {

  resObj[acc] = ''

  return resObj

}, {})

// uses keysObj to generate array of objects

var arrayOfObjects = subGrps.map(subGrp => ({...keysObj, Subgroup: subGrp}))

console.log(arrayOfObjects)

Answer 3

如果你想特别对待它，我不知道为什么与其他键混在一起，但在这里你去："Subgroup"

const [sgKey, ...keys] = ["Subgroup", "0-3", "3-10", "11-40"];

const subGrps = ["SP_20k", "SP_40k", "SP_60k"];

const result = subGrps.map(sg => {

  const obj = {

    [sgKey]: sg

  }

  for (const k of keys) {

    obj[k] = ''

  }

  return obj

});

console.log(result)

Answer 4

您需要执行以下操作：

var keys = ["Subgroup", "0-3", "3-10", "11-40"];

var subGrps = ["SP_20k", "SP_40k", "SP_60k"];

var arrayOfObjects = [];

subGrps.forEach(function(id) {

  var obj = {}

  keys.forEach(function(item) {

    if (item === "Subgroup") {

      obj[item]= id

      arrayOfObjects.push(obj);

    } else {

      obj[item] = ""

      arrayOfObjects.push(obj);

    }

  });

});

console.log(arrayOfObjects);

Answer 5

试试这个，

const arr = [];

subGrps.forEach(subGrp => {

   const obj = {}

   keys.forEach(key => obj[key] = (key === 'Subgroup') ? subGrp : '' );

   arr.push(obj);

})

console.log(arr)