如果数组在对象中并且对象在下一个数组中，如何在数组中的对象中获取值？答案

【问题标题】：How get value in the object in the array, if array is in the object and the object in the next array?如果数组在对象中并且对象在下一个数组中，如何在数组中的对象中获取值？
【发布时间】：2019-10-26 15:44:34
【问题描述】：

预期效果：迭代数组中的对象，在数组comments 中的对象中获取值示例“电子邮件”。我想拼写数组和嵌套对象和数组并返回“电子邮件”值。当我得到数组comments 时，我尝试在对象中获取价值电子邮件我有错误email is undefined

let scores =  [
  {
    "userId": 1,
    "id": 1,
    "title": "bbbb",
    "project": "JS",
    "completed": false,
    "comments": [
      {
        "itemId": 1,
        "id": 1,
        "name": "provident id voluptas",
        "email": "Meghan_Littel@rene.us",
        "body": "sdsdsd"
      },
      {
        "itemId": 1,
        "id": 2,
        "name": "provident id voluptas",
        "email": "fdfdfdf_Littel@rene.us",
        "body": "sdsdsd"
      }
    ]
  },
 {
    "userId": 1,
    "id": 2,
    "title": "ggggg",
    "comments": [
      {
        "itemId": 2,
        "id": 1,
        "name": "odio adipisci rerum aut animi",
        "email": "Nikita@garfield.biz",
        "body": "dsdsdsd"
      }
    ]
  }
]


let obj;

for (var key in scores) {
      obj = scores[key];
      console.log(obj.comments); //return objects array
    }

 for (var key in ob) {
      let ob1 = ob[key];
      console.log(ob1[email]); //return email is undefined
    }

【问题讨论】：

标签： javascript arrays object ecmascript-6 javascript-objects

【解决方案1】：

您还需要迭代comments 并获取属性email。

使用for ... of statement 和destructuring assignment。

let scores = [{ userId: 1, id: 1, title: "bbbb", project: "JS", completed: false, comments: [{ itemId: 1, id: 1, name: "provident id voluptas", email: "Meghan_Littel@rene.us", body: "sdsdsd" }, { itemId: 1, id: 2, name: "provident id voluptas", email: "fdfdfdf_Littel@rene.us", body: "sdsdsd" }] }, { userId: 1, id: 2, title: "ggggg", comments: [{ itemId: 2, id: 1, name: "odio adipisci rerum aut animi", email: "Nikita@garfield.biz", body: "dsdsdsd" }] }];

for (let { comments } of scores) {
    for (let { email } of comments) {
        console.log(email);
    }
}

与Array#forEach

let scores = [{ userId: 1, id: 1, title: "bbbb", project: "JS", completed: false, comments: [{ itemId: 1, id: 1, name: "provident id voluptas", email: "Meghan_Littel@rene.us", body: "sdsdsd" }, { itemId: 1, id: 2, name: "provident id voluptas", email: "fdfdfdf_Littel@rene.us", body: "sdsdsd" }] }, { userId: 1, id: 2, title: "ggggg", comments: [{ itemId: 2, id: 1, name: "odio adipisci rerum aut animi", email: "Nikita@garfield.biz", body: "dsdsdsd" }] }];

scores.forEach(({ comments }) => comments.forEach(({ email }) => console.log(email)));

【讨论】：

如何拉一些没有数组的对象。我有结果comments:[{},{},{}]。我想要结果 {},{},{}
你可以拿走这个对象。你想用它做什么？
从数组comments拉取对象并推送到另一个数组
只需将对象推送到结果数组。 for (let { comments } of scores) result.push(...comments);.

【解决方案2】：

所有电子邮件都需要一个嵌套循环，但如果您知道要查找的电子邮件的索引，则只需将该索引传递给comments[index]

scores[current_iteration].comments[current_iteration].email

【讨论】：