如何為數組中的對象賦予其屬性？

Question

例如，我正在創建一個對象數組，該數組中的每個對象都應該描述一本書。

在我的腦海中，這就是我所看到的：

var booksArray = ["Always Running", "Hatchet", "Autobiography of Malcolm X", "Che Guevara: A Revolutionary Life", "The Prince"];

我還應該提供以下屬性：

標題：作者：已經閱讀：（布爾值）

所以說這就是我的代碼的樣子，我不知道我是否正確，看看book1，book2等如何未連接到數組。

    var booksListArray = ["Always Running", "Hatchet", "Autobiography of Malcolm X", "Che Guevara: A Revolutionary Life", "The Prince"];

    var book1 = {
        title: "Always Running",
        author: "Luis J. Rodriguez",
        alreadyRead: true
    }

    var boook2 = {
        tite: "Hatchet",
        author: "Gary Paulsen",
        alreadyRead: true
    }

Answer 1

您可以將book對象直接放入數組中：

var books = [
    { title: "Always Running", author: "Luis J. Rodriguez", alreadyRead: true },
    { title: "Hatchet", author: "Gary Paulsen", alreadyRead: true },
    // etc
];

請注意，如果要擴展規模（例如，擁有成千上萬的Book對象實例），則使用Constructor函數時，JavaScript引擎可以為許多具有相同屬性的對象優化其內部內存（例如，不存儲屬性名稱）以每個對象實例為例）：

function Book(title, author, alreadyRead) {
    this.title = title;
    this.author = author;
    this.alreadyRead = alreadyRead;
}

您將像這樣使用它：

var books = [
    new Book( "Always Running", "Luis J. Rodriguez", true ),
    new Book( "Hatchet", "Gary Paulsen", true ),
    // etc
];

Answer 2

這很容易...您已經創建了一個具有book1和book2的對象，只需將它們分成如下數組即可：

var booksListArray = [
   {
    title: "Always Running",
    author: "Luis J. Rodriguez",
    alreadyRead: true
   },
   {
    tite: "Hatchet",
    author: "Gary Paulsen",
    alreadyRead: true
   }
  ]

然后，您可以訪問像這樣的書詳細信息（示例將顯示第一本書的標題）：

 booksListArray[0].title

Answer 3

編輯：更新了代碼以顯示已讀和未讀的書。

使用push()方法將對象插入數組。

 var booksListArray = ["Always Running", "Hatchet", "Autobiography of Malcolm X", "Che Guevara: A Revolutionary Life", "The Prince"]; var book1 = { title: "Always Running", author: "Luis J. Rodriguez", alreadyRead: true } var book2 = { title: "Hatchet", author: "Gary Paulsen", alreadyRead: true } var books = []; books.push(book1); books.push(book2); console.log(books); books.forEach(function(book){ if(book.alreadyRead){ console.log('I have read ' + book.title + ' by ' + book.author); } else { console.log('I haven\\'t read ' + book.title+ ' by ' + book.author); } }); 

Answer 4

盡管所有答案都可以滿足這個問題。 我將提供有關數組的更多信息。

基本上，數組只是事物的集合。 這些東西可以是數字，字符串，對象等。在大多數語言中，您可以創建一個只能容納一種數據的數組。 例如，在Java中，數組可以是數字的集合

[1,4,6,2,8] 

或字符串

["string1","string2","string with spaces"]

但是不能是不同類型的項目的集合。 您必須先定義數據類型，然后才能使用數組。 例如下面的組合。

[22,"string with numbers", 45.77]

但是在JS中，數組更靈活。 您可以將任何類型的項目存儲在單個數組中。

var bookIds= [1001,1002,1003];    
var randomArray = [3,'string',{userID:345},bookIds];

現在回到問題所在，我們需要將每本書的大量信息存儲在一個數組中。 由於數組可以存儲對象，而對象本質上是另一個具有將信息存儲在鍵值對中的數據結構。

您可以創建一個描述每本書的對象，然后將每個對象添加到數組中

var book1 = {
    title: "Always Running",
    author: "Luis J. Rodriguez",
    alreadyRead: true
}
var book2 = {
    tite: "Hatchet",
    author: "Gary Paulsen",
    alreadyRead: true
}

下面是一些聲明數組的方法

//declaring empty array
var books = []; 

// by doing this, you are just creating an array of strings where each string gives you the name of the book
var booksArray = ["Always Running", "Hatchet", "Autobiography of Malcolm X", "Che Guevara: A Revolutionary Life", "The Prince"];

//declaring and initializing at the same time with two objects- book1 and book2, of course both need to be declared before this line
var books = [book1, book2] 

//declaring array with some book IDs. These books ids then can be used to access other arrays or objects which contain all the books information.
var books = ['1001', '1002'] 

如果數組為空，則需要添加book對象，為此我們可以使用JS提供的push和pop方法

var book1 = {
    title: "Always Running",
    author: "Luis J. Rodriguez",
    alreadyRead: true
}
var book2 = {
    tite: "Hatchet",
    author: "Gary Paulsen",
    alreadyRead: true
}
books.push(book1);
books.push(book2);

最后一個簡單的練習給您。 創建一個根據以下要求保存信息的數組

我需要存儲一些書籍和作者

Book details: 
book_id - should be a number
name - should be a string
authors - a list of authors as there can be multiple authors for one book, here you can again use array of author_ids
alreadyRead - a boolean value

Author details : 
author_id - author id, should be a number
name - should be a string
books - a list of books written, maybe an array of book_ids that should represent the books this author has written