Javascript将对象列表转换为地图映射

Question

我是 Javascript 的新手。 我正在使用 javascript 将对象列表转换为地图地图。
下面是我写的代码。

 var person = { firstName: "John", lastName: "Doe", rank: 0, rollNo: "0201", school: "test", id: 0 }; var person1 = { firstName: "John1", lastName: "Doe1", rank: 0, rollNo: "0201", school: "test1", id: 1 }; var testList = [] var testList1 = [] var slotObject = {} var slotObjectMap = {}; var finalObject = {}; testList.push(person); testList.push(person1); console.log(testList); for (let i = 0; i < testList.length; i++) { slotObject["firstName"] = testList[i].firstName; slotObject["lastName"] = testList[i].lastName; slotObject["rollNo"] = testList[i].rollNo; slotObject["rank"] = testList[i].rank; slotObject["school"] = testList[i].school; testList1.push(slotObject); if (finalObject[testList[i]]) { console.log("yes"); slotObjectMap = {}; } else { slotObjectMap = finalObject[testList[i].school]; } slotObjectMap[testList[i].id] = slotObject; finalObject[testList[i].school] = slotObjectMap; } console.log(slotObjectMap); console.log(finalObject); // Display some data from the object: document.getElementById("demo").innerHTML = person.firstName;

 <h2>JavaScript Objects</h2> <p id="demo"></p>

我的预期输出是：

{ test:{
   0:{firstName: "John", lastName:"Doe", rank:0, rollNo:"0201", school:"test"}, 
   }, 
 test1:{
   1:{firstName: "John1", lastName:"Doe1", rank:0, rollNo:"0201", school:"test1"}
   }
}

我上面的代码没有按预期工作。 不知道哪里出了问题。
请帮忙。

我的最终目标是将上面的对象（人，人 1）转换为下面的输出。 这可以使用数组减少吗？

[ { additionalInfo : ''
  , school         : 'test'
  , randomValue    : ''
  , studentInfo: 
    [ { rank      : 0
      , rollNo    : '0201'
      , firstName : 'John'
      , lastName  : 'Doe'
  } ] } 
, { additionalInfo : ''
  , school         : 'test1'
  , randomValue    : ''
  , studentInfo: 
    [ { rank      : 0
      , rollNo    : '0201'
      , firstName : 'John1'
      , lastName  : 'Doe1'
  } ] } 
] 

Answer 1

不是 100% 确定您使用 slotObject 等的所有代码都是关于什么的。

但是看看你的预期输出，看起来你想使用reduce，学校作为你用来减少到..的键。

例如。

 var person = { firstName: "John", lastName: "Doe", rank: 0, rollNo: "0201", school: "test", id: 0 }; var person1 = { firstName: "John1", lastName: "Doe1", rank: 0, rollNo: "0201", school: "test1", id: 1 }; const r = [person, person1].reduce( (a, v) => { //extract school & id, const {school, id, ...other} = v; //lets make sure school exists a[school] = a[school] || {}; //lets add back school to other, and assign //and use id as another sub key into school. a[school][id] = {...other ,school}; return a}, {}); console.log(r);

 <h2>JavaScript Objects</h2> <p id="demo"></p>

Answer 2

您不能使用 Array.map，因为此方法返回一个 Array 而您需要一个 Object。
只需了解array.reduce和Destructuring 赋值

 var person = { firstName:"John", lastName:"Doe", rank:0, rollNo:"0201", school:"test", id:0 } , person1 = { firstName:"John1", lastName:"Doe1", rank:0, rollNo:"0201", school:"test1", id:1 } ; let testList = [ person, person1 ] let result = testList.reduce((r,{school, id, ...info})=> { r[school] = {} r[school][id] = {...info, school } return r } ,{}) console.log( result )

 .as-console-wrapper { max-height: 100% !important; top: 0; }

对于问题更新
（以及来自 PO 的评论部分 - 在聊天中）

 let testList = [ { firstName:"John", lastName:"Doe", rank:0, rollNo:"0201", school:"test", id:1 } , { firstName:"John1", lastName:"Doe1", rank:0, rollNo:"0201", school:"test1", id:2 } , { firstName:"John2", lastName:"Doe2", rank:0, rollNo:"0202", school:"test1", id:3 } , { firstName:"John3", lastName:"Doe3", rank:0, rollNo:"0203", school:"test", id:5 } ] , result = testList.reduce((res,{ firstName, lastName, rank, rollNo, school })=> { let line = res.find(x=>x.school===school) if (!line) { line = { additionalInfo:'', school, randomValue:'', studentInfo:[] } res.push(line) } line.studentInfo.push({ rank, rollNo, firstName, lastName }) return res } ,[] ) console.log( result )

 .as-console-wrapper { max-height: 100% !important; top: 0; }