Remove object property from the nested object in the array

Question

I have the following array of books. I want a write a function that receives the target book and the language, removes that book (key, value) from the nested object and returns the new array.

let books = [
  {
    language: 'spanish',
    books: {
      book_1: 'book1_spanish',
      book_2: 'book2_spanish',
      book_3: 'book3_spanish'
    }
  },
  {
    language: 'italian',
    books: {
      book_1: 'book1_italian',
      book_2: 'book2_italian',
      book_3: 'book3_italian'
    }
  }
];

let targetBook = { book_1: 'book1_spanish' };
let language = 'spanish';

I am stuck at looping over the nested object.

function removeTargetBook(lan, target) {
  return books.map(book => {
    if (book.language == lan) {
      Object.values(book).map(value => {});
    }
  });
}

It should return the same array without book_1: 'book1_spanish'. This is my stackblitz: https://stackblitz.com/edit/js-yxcrbq

Thanks.

Take a look at this: developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/… — AGE
– AGE, Commented Aug 30, 2021 at 19:18

AGE · Accepted Answer · 2021-08-30 19:33:07Z

2

You want to be using the delete operator.

I took the liberty of expanding on your code a little to show you how using the key of the object in a forEach loop is more efficient than doing a key / value pair comparison. Also note that I am leaving the original books object intact, this is important for unit testable code and data integrity, but you can change/implement as you need.

let books = [
  {
    language: 'spanish',
    books: {
      book_1: 'book1_spanish',
      book_2: 'book2_spanish',
      book_3: 'book3_spanish'
    }
  },
  {
    language: 'italian',
    books: {
      book_1: 'book1_italian',
      book_2: 'book2_italian',
      book_3: 'book3_italian'
    }
  }
];

let targetBook = { book_1: 'book1_spanish' };
let language = 'spanish';
let target = Object.keys(targetBook)[0]; // we only need the 'key' of the targetBook
let result;

function removeTargetBook(books, lan, target) {
  books.forEach(elem => { // some instead of forEach works here as well
    elem.language === lan && (delete elem.books[target]);
  });
  
  return books;
}
// multiple tests for correctness
result = removeTargetBook(books, language, 'fool proof test');
console.log(result);
result = removeTargetBook(books, language, target);
console.log(result);
result = removeTargetBook(books, language, 'book_2');
console.log(result);
result = removeTargetBook(books, language, 'book_3');
console.log(result);

answered Aug 30, 2021 at 19:33

AGE

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2 Comments

Ricardo Saracino Over a year ago

@zana10 sometimes you dont need a function, in the above solution i wouldnt use a function for a single callback unless you are "deleting books" in multiple places

AGE Over a year ago

the data structure being used does not allow for a single item search since everything is stored in an array of objects, I would re-arrange the data structure to be a large object with key being language and value being the content of books, this way as @RicardoSaracino mentioned, you will be able to bypass the need of a callback function and also a loop to match by language

Vulwsztyn · Accepted Answer · 2021-08-30 19:30:08Z

My far too complicated version:

let books = [{
    language: 'spanish',
    books: {
      book_1: 'book1_spanish',
      book_2: 'book2_spanish',
      book_3: 'book3_spanish'
    }
  },
  {
    language: 'italian',
    books: {
      book_1: 'book1_italian',
      book_2: 'book2_italian',
      book_3: 'book3_italian'
    }
  }
];

let targetBook = {
  book_1: 'book1_spanish'
};
let language = 'spanish';

function removeTargetBook(lan, target) {
  return books.map(book => {
    if (book.language === lan) {

      return {
        language: book.language,
        books: Object.assign(...Object.keys(book.books).map((key) => ({
          [key]: book.books[key]
        })).filter((e) => (Object.keys(e)[0] !== Object.keys(target)[0]) && Object.values(e)[0] !== Object.values(target)[0])),
      }
    } else {
      return book
    }
  })
}
console.log(removeTargetBook(language, targetBook))

Lytion · Accepted Answer · 2021-08-30 19:25:32Z

0

I think something like this should work

function removeTargetBook(lan, target) {
  books.some(book => {
    if (book.language == lan) {
      delete book.books[Object.keys(target)[0]];
      return true;
    }
  });
  return books
}

answered Aug 30, 2021 at 19:25

Lytion

1

1 Comment

Community Over a year ago

Please add further details to expand on your answer, such as working code or documentation citations.

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