规范化性能：allIds 数组与 Object.entries 函数

Question

在 redux 和其他情况下，我们可能希望规范化 JavaScript 本质上是关系的对象，而不是具有深层嵌套的对象。

例如，redux 显示了一个建议拆分代码的方法：

const byID = {
  '1': {
    some: 'object'
  },
  '2': {
    some: 'objectAgain'
  },
  '3': {
    some: 'objectAnotherAgain'
  },
};
const allIds = ['1', '2', '3'];

Redux Recommended Recipe

但是，持有 allIds 数组与仅调用类似以下内容相比有什么好处：

Object.keys(byId);

Object Keys Recipe

将所有对象键作为数组保存更快吗？还是它们具有相似的时间复杂度？将每个键保存在数组中不会是重复代码吗？

Answer 1

Object.keys(byId) returns 与allIds完全相同的数组，但redux的目的是将所有数据存储尽可能扁平 一个对象，对吧？在对象外部调用 Object.keys() 方法而不保存它与此相反...

var array = {
  posts: {
    byId: {
      "post1": {
        id: "post1",
        author: "user1",
        body: "......",
        comments: ["comment1", "comment2"]
      },
      "post2": {
        id: "post2",
        author: "user2",
        body: "......",
        comments: ["comment3", "comment4", "comment5"]
      }
    },
    allIds: ["post1", "post2"]
  },
  comments: {
    byId: {
      "comment1": {
        id: "comment1",
        author: "user2",
        comment: ".....",
      },
      "comment2": {
        id: "comment2",
        author: "user3",
        comment: ".....",
      },
      "comment3": {
        id: "comment3",
        author: "user3",
        comment: ".....",
      },
      "comment4": {
        id: "comment4",
        author: "user1",
        comment: ".....",
      },
      "comment5": {
        id: "comment5",
        author: "user3",
        comment: ".....",
      },
    },
    allIds: ["comment1", "comment2", "comment3", "commment4", "comment5"]
  },
  users: {
    byId: {
      "user1": {
        username: "user1",
        name: "User 1",
      },
      "user2": {
        username: "user2",
        name: "User 2",
      },
      "user3": {
        username: "user3",
        name: "User 3",
      }
    },
    allIds: ["user1", "user2", "user3"]
  }
}

var keys = Object.keys(array.users.byId);
console.log(keys); // need to call a function where i should already know what i want
var simpleKeys = array.users.allIds
console.log(simpleKeys); // way faster too

Relevant links:

Object.keys()

normalized state

规范化性能：allIds 数组与 Object.entries 函数

Normalisation Performance: allIds array vs Object.entries function

javascript

normalization

redux