React Native：如何从导入的 JSON 文件中获取数组的长度？

Question

我想从导入的文件中获取 JSON 数组的长度，但它返回未定义。我可以从中访问任何元素。我猜问题是这里的“书”不是数组？

book.json:

[
  {
    "author" : "Bill",
    "total_chapters" : 14,
  },
  {
    "author" : "Chan",
    "total_chapters" : 29,
  },
:
]

App.js：

import * as books from './assets/book.json';

const author = books[60].author; //returns author
console.log('#books: ' + books.length); //undefined
console.log('books is ' + books.constructor); // Books is function Object() { [native code] }
console.log('books: ' + books); //books: [object Object]

Answer 1

感谢@snjmhj 的提示。书籍是一个对象，可以通过这种方式获得长度：

Object.values(books).length