JavaScript 将对象数组映射到新对象数组的最短方法？

Question

我有一个person对象数组，其中每个person都有一个由 name 和 image url 组成的profiles对象数组，以及一个由lat和long属性组成的addresses 对象列表，如下所示：

var listOfPersons = [{
    addresses : [{lat:11, long:11}, {lat:22, long:22}],
    profile: [{image:"some_url1", name: "peter parker"}]
},
{
    addresses : [{lat:33, long:33}, {lat:44, long:44}],
    profile: [{image:"some_url2", name: "bruce wayne"}]
}];

我需要创建一个新的对象数组，其中每个新对象对于每组lat long都有一个image 、 long 、 lat属性，如下所示：

var expectedResult = [
{
    image:"some_url1",
  lat:11,
  long:11
},
{
    image:"some_url1",
  lat:22,
  long:22
},
{
    image:"some_url1",
  lat:33,
  long:33
},
{
    image:"some_url1",
  lat:44,
  long:44
}
];

什么是最简单的办法（在编写代码的条款），以map \\ reduce第一阵列进入第二？

Answer 1

您可以使用嵌套的Array.flatMap()和Array.map()来迭代数组/地址/配置文件，并将image和lat , long属性组合到一个对象中：

 const listOfPersons = [{"addresses":[{"lat":11,"long":11},{"lat":22,"long":22}],"profile":[{"image":"some_url1","name":"peter parker"}]},{"addresses":[{"lat":33,"long":33},{"lat":44,"long":44}],"profile":[{"image":"some_url2","name":"bruce wayne"}]}]; const result = listOfPersons.flatMap(o => o.addresses.flatMap(({ lat, long }) => o.profile.map(({ image }) => ({ image, lat, long })) ) ); console.log(result);

如果您始终只使用第一个配置文件，则可以删除一层Array.flatMap() ：

 const listOfPersons = [{"addresses":[{"lat":11,"long":11},{"lat":22,"long":22}],"profile":[{"image":"some_url1","name":"peter parker"}]},{"addresses":[{"lat":33,"long":33},{"lat":44,"long":44}],"profile":[{"image":"some_url2","name":"bruce wayne"}]}]; const result = listOfPersons.flatMap(o => o.addresses.map(({ lat, long }) => ({ image: o.profile[0].image, lat, long })) ); console.log(result);

Answer 2

您可以将Array.prototype.reduce()与Array.prototype.forEach()结合使用。

reduce()的文档说明：

reduce() 方法在数组的每个元素上执行一个 reducer 函数（您提供的），从而产生单个输出值。

我认为以下方法对您有用：

 const listOfPersons = [{ addresses : [{lat:11, long:11}, {lat:22, long:22}], profile: [{image:"some_url1", name: "peter parker"}] }, { addresses : [{lat:33, long:33}, {lat:44, long:44}], profile: [{image:"some_url2", name: "bruce wayne"}] }]; const result = listOfPersons.reduce((acc, cur) => { cur.addresses.forEach(e => acc.push({ ...e, image: cur.profile[0].image })); return acc; }, []); console.log(result);

我希望这有帮助！

Answer 3

由于您要求编写代码最短：

 var listOfPersons = [{addresses: [{lat:11, long:11}, {lat:22, long:22}],profile: [{image:"some_url1", name: "peter parker"}]},{addresses:lat:33, long:33}, {lat:44, long:44}],profile: [{image:"some_url2", name: "bruce wayne"}]}]; const res = listOfPersons.reduce((r,{addresses:a,profile:[{image}]})=> [...r,...a.map(o=>({image,...o}))],[]); console.log(res);

这是格式和更好的变量名称：

 var listOfPersons = [{ addresses : [{lat:11, long:11}, {lat:22, long:22}], profile: [{image:"some_url1", name: "peter parker"}] }, { addresses : [{lat:33, long:33}, {lat:44, long:44}], profile: [{image:"some_url2", name: "bruce wayne"}] }]; const res = listOfPersons.reduce((acc, { addresses: adr, profile: [{image}] }) => [...acc, ...adr.map(a => ({image, ...a}) )], []); console.log(res);

Answer 4

var listOfPersons = [
  {
    addresses: [{ lat: 11, long: 11 }, { lat: 22, long: 22 }],
    profile: [{ image: "some_url1", name: "peter parker" }]
  },
  {
    addresses: [{ lat: 33, long: 33 }, { lat: 44, long: 44 }],
    profile: [{ image: "some_url2", name: "bruce wayne" }]
  }
];

var expectedResult = listOfPersons.reduce(
  (acc, person) => ([
    ...acc,
    ...person.addresses.map(
      address => ({ ...address, image: person.profile[0].image })
    )
  ]),
  []
)

假设您总是想要.profile的第一个结果，这将为您提供所需的内容

Answer 5

var listOfPersons = [{
    addresses : [{lat:11, long:11}, {lat:22, long:22}],
    profile: [{image:"some_url1", name: "peter parker"}]
},
{
    addresses : [{lat:33, long:33}, {lat:44, long:44}],
    profile: [{image:"some_url2", name: "bruce wayne"}]
}];


var expectedResult = [];
expectedResult.forEach(person => {
    person.addresses.forEach(address => expectedResult.push({image: person.profile[0].image, ...address}))
});