Question

我正在尝试创建一个JavaScript对象，该对象可以轻松地让我检查一本书中有多少章，以及某章中有多少经文。

我的计划是使对象具有这样的结构：

const amounts = {
    book: {
        bookNumber: 1,
        bookChapters: 50,
        chapter:
        {
            chapterNumber: 1,
            versesInChapter: 31
        },

        chapter:
        {
            chapterNumber: 2,
            versesInChapter: 25
        }
    },

    book: {
        bookNumber: 2,
        bookChapters: 40,
        chapter:
        {
            chapterNumber: 1,
            versesInChapter: 26
        },

        chapter:
        {
            chapterNumber: 2,
            versesInChapter: 22
        }
    }

}

如何基于变量值访问此类结构的嵌套值？例如，我可能有一个var bookNum = 2和var ChapterNum = 2，而我的目标是要获得第二本书第2章中的经文数量。我将如何编写这样的查询？

编辑：根据评论，我的对象结构也很糟糕，因此我想指出一个正确的结构，使我可以有效地访问大量经文。

Answer 1

您可以按照下面的方式重写您的无用金额，这将有助于操作

const books = [
 {
        bookNumber: 1,
        bookChapters: 50,
        chapter:[
        {
            chapterNumber: 1,
            versesInChapter: 31
        },
        {
            chapterNumber: 2,
            versesInChapter: 25
        }
    ],
}

    {
        bookNumber: 2,
        bookChapters: 40,
        chapter:[
        {
            chapterNumber: 1,
            versesInChapter: 26
        },

        {
            chapterNumber: 2,
            versesInChapter: 22
        }
    ]
    }

]

const books = [{
    bookNumber: 1,
    bookChapters: 50,
    chapter: [{
        chapterNumber: 1,
        versesInChapter: 31
      },
      {
        chapterNumber: 2,
        versesInChapter: 25
      }
    ],
  },

  {
    bookNumber: 2,
    bookChapters: 40,
    chapter: [{
        chapterNumber: 1,
        versesInChapter: 26
      },

      {
        chapterNumber: 2,
        versesInChapter: 22
      }
    ]
  }

]

var serach = books.filter(function(book) {
  //console.log("books",book);
  return book.bookNumber == 1;
})[0];
console.log("Searched book!", serach)

//And for desired result you can use forEach and filter 
var num = 2,
  chap = 1,
  found_chapter;

books.forEach(function(book) {
  if (book.bookNumber == num) { //found the book
    console.log("found book", book);
    found_chapter = book.chapter.filter(function(chapter) {
      return chapter.chapterNumber == chap; //found chapter WRT found book
    })[0]

  }
});
console.log("found chapter-", found_chapter, "--found verse", found_chapter.versesInChapter)

作为上面的代码段，您可以过滤出搜索数据，并可以轻松地再次循环查找所需结果

希望这对您有帮助！

Answer 2

您可以通过两种方式构造此数据：作为array或object。

方法1（对象）

由于书籍被bookNumber索引，因此bookNumber成为对象中的键是有意义的。

这可以简化为：

{
  bookNumber: {
    chapterNumber: versesInChapter, 
     ...
  }, 
  ...
}

我在代码中添加了一些注释以帮助澄清。

const books = {
  1: {
    1: 31,
    2: 25
  },
  2 /*bookNumber*/: {
    1 /*chapterNumber*/: 26 /*versesInChapter*/ ,
    2 /*chapterNumber*/: 22 /*versesInChapter*/
  }
};

// es6 style function. Same as `function getVerses(bookNum, chapterNum){...}`
getVerses = (bookNum, chapterNum) => {
  if (books[bookNum] && books[bookNum][chapterNum]) {
    return books[bookNum][chapterNum];
  } else {
    // Notify that the index is not set
    console.warn('Warning: Book or chapter number is not defined!');
    // Return 0 as deafult
    return 0;
  }
}

let bookNum = 2;
let chapterNum = 2;
let numOfVerses = getVerses(bookNum, chapterNum);
console.log(`Book ${bookNum} chapter ${chapterNum} has ${numOfVerses} verses.`);

方法2（数组）

如果这些书是连续的，则数组也可以工作。

[
  [versesInChapter/*1*/,versesInChapter/*2*/, ...],
  ...
]

例如：

const books = [
   [31,25],
   [26,22]
];

// es6 style function. Same as `function getVerses(bookNum, chapterNum){...}`
getVerses = (bookNum, chapterNum) => {
  bookNum--;
  chapterNum--;
  if (books[bookNum] && books[bookNum][chapterNum]) {
    return books[bookNum][chapterNum];
  } else {
    // Notify that the index is not set
    console.warn('Warning: Book or chapter number is not defined!');
    // Return 0 as deafult
    return 0;
  }
}

let bookNum = 2;
let chapterNum = 2;
let numOfVerses = getVerses(bookNum, chapterNum);
console.log(`Book ${bookNum} chapter ${chapterNum} has ${numOfVerses} verses.`);

希望这会有所帮助，

Answer 3

您可以将books和chapters构造为数组。然后，您可以访问其中的每条数据，例如：

var books = [
  {
    name: "Book1",
    chapters: [
      { countOfVerses: 31 },
      { countOfVerses: 20 }
    ]
  },
  {
    name: "Book2",
    chapters: [
      { countOfVerses: 12 },
      { countOfVerses: 20 },
      { countOfVerses: 16 },
      { countOfVerses: 22 }
    ]
  }    
];

for (let book of books){
  let name = book.name; // Now we know which book it is...
  let chapterCount = book.chapters.length; // ...and how many chapters it has
  console.log(`${name} has ${chapterCount} chapters:`)

  for (let i = 0; i < chapterCount; i++){
    let chapter = book.chapters[i]; // Look in each chapter in the book...
    let verses = chapter.countOfVerses; //...and get the countOfVerses property
    console.log(`  Chapter ${i+1} has ${verses} verses`);
  }
}

基于字符串变量访问嵌套的javascript对象

3 个答案: