如何从 JSON Node.js 获取特定的数据值？

Question

这是我的 JSON 文件输出：

let employees = [{
  "id":1,
  "name":"Lann",
  "username":"brot",
  "email":"b@sd.com",
  "address": {
    "city":"Gweh",
    "zipcode":"92998-3874",
    "geo": {
      "lat":"45",
      "lng":"77"
    }
  }
}]

我如何从下面获取 ID、姓名和电子邮件：

{
  "id":1,
  "name":"Lann",
  "email":"b@sd.com"
}

Answer 1

如果您的数组只有一个元素，您可以只访问信息，无需像这样构建另一个数组：employees[0].id、employees[0].name、employees[0].email，或者您可以使用对象解构提取一个对象

let employees = [{
  "id": 1,
  "name": "Lann",
  "username": "brot",
  "email": "b@sd.com",
  "address": {
    "city": "Gweh",
    "zipcode": "92998-3874",
    "geo": {
      "lat": "45",
      "lng": "77"
    }
  }
}];
const picked = (({ id, name, email }) => ({  id, name, email }))(employees[0]);
console.log(picked);

但是如果你的数组有更多的员工，我认为你需要做的是通过 id 或 name 搜索并返回一个信息最少的对象，你可以这样做

let employees = [{
  "id": 1,
  "name": "Lann",
  "username": "brot",
  "email": "b@sd.com",
  "address": {
    "city": "Gweh",
    "zipcode": "92998-3874",
    "geo": {
      "lat": "45",
      "lng": "77"
    }
  }
}];
let employee = employees.find(o => o.name === 'Lann');
let picked = (({ id, name,email }) => ({ id, name,email }))(employee);
console.log(picked);

Answer 2

您可以使用地图存档。

let employees = [{
          "id":1,
          "name":"Lann",
          "username":"brot",
          "email":"b@sd.com",
          "address":{
             "city":"Gweh",
             "zipcode":"92998-3874",
             "geo":{
                "lat":"45",
                "lng":"77"
             }
          }
          }]
const data = employees.map(o => ({ id: o.id, name: o.name, email:o.email }));
console.log(data[0]);

Answer 3

您可以通过使用数组解构来简单地做到这一点。

let employees = [{
          "id":1,
          "name":"Lann",
          "username":"brot",
          "email":"b@sd.com",
          "address":{
             "city":"Gweh",
             "zipcode":"92998-3874",
             "geo":{
                "lat":"45",
                "lng":"77"
             }
          }}];

// Destructuring array
const [employee] = employees;

** 现在从这里employee 是一个对象，您可以像访问其他对象一样正常访问它的属性。获取id,name,username:**

employee.id;
employee.name;
employee.username;

Answer 4

如果它包含多个项目，您还可以循环通过您的输入并获得一组收缩项目：

let employees = [{
  "id": 1,
  "name": "Lann",
  "username": "brot",
  "email": "b@sd.com",
  "address": {
    "city": "Gweh",
    "zipcode": "92998-3874",
    "geo": {
      "lat": "45",
      "lng": "77"
    }
  }
}]

let shrink = [];

for (let employee of employees) {
  shrink.push({
    id: employee.id,
    name: employee.name,
    email: employee.email
  });
}

console.log(shrink);