ES6 - 從現有數據創建新的 object，只使用一個屬性，並刪除任何重復項？

Question

我有一組對象作為data返回給我，我正在尋找創建一組新數據，同時保留舊數據以供將來使用。

我正在嘗試遍歷給定的數據以創建一組僅包含年齡的新數據，但也會刪除任何重復項。 我不太確定從哪里開始。

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"
    }
]

我想結束的是這樣的：

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

Answer 1

或者您可以只使用Set來消除重復項：

// 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，這么多方法，這是另一種方法：純功能：

 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

您可以將.map和.filter與Set結合使用：

 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);