Question

我有一组对象以data的形式返回给我，我希望创建一组新数据，同时保留旧数据以备将来使用。

我正在尝试遍历给定的数据以创建一组新数据，该数据集不仅包含年龄，而且还删除了所有重复项。我不太确定从哪里开始。

data = [
    {
        "firstName": "John",
        "lastName": "Doe",
        "age": "99"
    }, 
    {
        "firstName": "Jimmy",
        "lastName": "Hendricks",
        "age": "50"
    }, 
    {
        "firstName": "William",
        "lastName": "Shakespeare",
        "age": "22"
    }, 
    {
        "firstName": "Jane",
        "lastName": "Eyre",
        "age": "50"
    }
]

我最终想得到的是这样的东西：

newData = [
        {"age": "99"}, 
        {"age": "50"}, 
        {"age": "22"}
]

Answer 1

或者您也可以使用Set来消除重复项：

// ages variable contain just the ages
const ages = data.map(person => person.age);
// new Set(ages) will remove duplicated values:
const newSet = Array.from(new Set(ages)).map(age => ({ age: age }));

Answer 2

哇，方法太多了！这是另一个纯粹的功能：

data = [ { "firstName": "John", "lastName": "Doe", "age": "99" }, { "firstName": "Jimmy", "lastName": "Hendricks", "age": "50" }, { "firstName": "William", "lastName": "Shakespeare", "age": "22" }, { "firstName": "Jane", "lastName": "Eyre", "age": "50" } ]; 

console.log(
 Object.keys(data.reduce((obj,o)=>
 	    (obj[o.age]=1,obj),{}))
.map(k=>({age:k}))
)

Answer 3

let newData = [];
let uniques = [];
data.forEach(el => {
    if(!uniques.includes(el.age)){
      newData.push({age: el.age});
      uniques.push(el.age);
}
});

Answer 4

您可以将.map和.filter与Set结合使用：

const data = [
    {
        "firstName": "John",
        "lastName": "Doe",
        "age": "99"
    }, 
    {
        "firstName": "Jimmy",
        "lastName": "Hendricks",
        "age": "50"
    }, 
    {
        "firstName": "William",
        "lastName": "Shakespeare",
        "age": "22"
    }, 
    {
        "firstName": "Jane",
        "lastName": "Eyre",
        "age": "50"
    }
]

const newdata = data
  .map(({age}) => ({age})) // convert `{age: <value of age>}`
  .filter(function({age}) {
    const isUnique = !this.has(age); //check if already present
    this.add(age); //add anyway

    return isUnique; //filter keeping uniques
  }, new Set());//use a Set as the `this` context for the filter
  
console.log(newdata);

ES6-仅使用一个属性从现有数据中创建新对象，并删除任何重复项？

4 个答案: