React Native - If / Else with a variable

Question

I have to create two different variables (with the same name) as option for axios (the req data).

  var indentifiers = entry.volumeInfo.industryIdentifiers;

  console.log(indentifiers.length);


  if (indentifiers.length === 1) {
    const item = {
      isbn_13: 'Not Provided',
      isbn_10: entry.volumeInfo.industryIdentifiers[0].identifier,
      kind: entry.kind,
      title: entry.volumeInfo.title,
      authors: entry.volumeInfo.authors,
      publishedDate: entry.volumeInfo.publishedDate,
      language: entry.volumeInfo.language,
      image1: entry.volumeInfo.imageLinks.thumbnail,
    };
  } else if (indentifiers.length === 2) {
    const item = {
      isbn_13: entry.volumeInfo.industryIdentifiers[1].identifier,
      isbn_10: entry.volumeInfo.industryIdentifiers[0].identifier,
      kind: entry.kind,
      title: entry.volumeInfo.title,
      authors: entry.volumeInfo.authors,
      publishedDate: entry.volumeInfo.publishedDate,
      language: entry.volumeInfo.language,
      image1: entry.volumeInfo.imageLinks.thumbnail,
    };
  }

axios:

 const res = await axios.post(
        'http://74c26025c4e2.ngrok.io/api/database/addbook',
        item,
        config,
      );

Obviously when I put the variable into if/else is not reachable by the rest. What can I do? thanks

Define it using let above the if statement, and mutate it accordingly — MorKadosh
– MorKadosh, Commented Jun 11, 2020 at 12:33

Stéphane Veyret · Accepted Answer · 2020-06-11 15:26:12Z

What if neither test succeed? You don't have a pure else statement in your example, so are you sure that undefined is allowed for item?

If so, as @marco-disco suggested, you can define a variable above your first if statement:

let item
if (indentifiers.length === 1) {
    item = {
      isbn_13: 'Not Provided',
      isbn_10: entry.volumeInfo.industryIdentifiers[0].identifier,
      kind: entry.kind,
      title: entry.volumeInfo.title,
      authors: entry.volumeInfo.authors,
      publishedDate: entry.volumeInfo.publishedDate,
      language: entry.volumeInfo.language,
      image1: entry.volumeInfo.imageLinks.thumbnail,
    };
  } else if (indentifiers.length === 2) {
    item = {
      isbn_13: entry.volumeInfo.industryIdentifiers[1].identifier,
      isbn_10: entry.volumeInfo.industryIdentifiers[0].identifier,
      kind: entry.kind,
      title: entry.volumeInfo.title,
      authors: entry.volumeInfo.authors,
      publishedDate: entry.volumeInfo.publishedDate,
      language: entry.volumeInfo.language,
      image1: entry.volumeInfo.imageLinks.thumbnail,
    };
  }

If you really want item to be a const, you can use a ternary operator:

const item = (indentifiers.length === 1) ? {
    const item = {
      isbn_13: 'Not Provided',
      isbn_10: entry.volumeInfo.industryIdentifiers[0].identifier,
      kind: entry.kind,
      title: entry.volumeInfo.title,
      authors: entry.volumeInfo.authors,
      publishedDate: entry.volumeInfo.publishedDate,
      language: entry.volumeInfo.language,
      image1: entry.volumeInfo.imageLinks.thumbnail,
    };
  } : (indentifiers.length === 2) ? {
    const item = {
      isbn_13: entry.volumeInfo.industryIdentifiers[1].identifier,
      isbn_10: entry.volumeInfo.industryIdentifiers[0].identifier,
      kind: entry.kind,
      title: entry.volumeInfo.title,
      authors: entry.volumeInfo.authors,
      publishedDate: entry.volumeInfo.publishedDate,
      language: entry.volumeInfo.language,
      image1: entry.volumeInfo.imageLinks.thumbnail,
    };
  } : undefined

or use an IIFE (immediately invoked function expression):

const item = (() => {
  if (indentifiers.length === 1) {
    return {
      isbn_13: 'Not Provided',
      isbn_10: entry.volumeInfo.industryIdentifiers[0].identifier,
      kind: entry.kind,
      title: entry.volumeInfo.title,
      authors: entry.volumeInfo.authors,
      publishedDate: entry.volumeInfo.publishedDate,
      language: entry.volumeInfo.language,
      image1: entry.volumeInfo.imageLinks.thumbnail,
    };
  } else if (indentifiers.length === 2) {
    return {
      isbn_13: entry.volumeInfo.industryIdentifiers[1].identifier,
      isbn_10: entry.volumeInfo.industryIdentifiers[0].identifier,
      kind: entry.kind,
      title: entry.volumeInfo.title,
      authors: entry.volumeInfo.authors,
      publishedDate: entry.volumeInfo.publishedDate,
      language: entry.volumeInfo.language,
      image1: entry.volumeInfo.imageLinks.thumbnail,
    };
  } else {
    return undefined
  }
})()

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