freecodecamp--freecodecamp/curriculum/challenges/english/blocks/daily-coding-challenges-javascript/69e2383af7832c8032603b8f.md

id, title, challengeType, dashedName

id	title	challengeType	dashedName
69e2383af7832c8032603b8f	Challenge 273: ISBN-13 Validator	28	challenge-273

--description--

Given a string, determine if it is a valid ISBN-13 number.

A valid ISBN-13:

• Contains only digits and hyphens
• Has exactly 13 digits after removing hyphens
• Passes the following check:
  1. Multiply each digit by 1 or 3, alternating (multiply the first digit by 1, the second by 3, the third by 1, and so on).
  2. The sum of the results must be divisible by 10.

--hints--

isValidIsbn13("9780306406157") should return true.

assert.isTrue(isValidIsbn13("9780306406157"));

isValidIsbn13("97803064061570") should return false.

assert.isFalse(isValidIsbn13("97803064061570"));

isValidIsbn13("978-0-13-595705-9") should return true.

assert.isTrue(isValidIsbn13("978-0-13-595705-9"));

isValidIsbn13("978-030-64061A-4") should return false.

assert.isFalse(isValidIsbn13("978-030-64061A-4"));

isValidIsbn13("9-7-8-0-1-3-4-7-5-7-5-9-9") should return true.

assert.isTrue(isValidIsbn13("9-7-8-0-1-3-4-7-5-7-5-9-9"));

--seed--

--seed-contents--

function isValidIsbn13(str) {

  return str;
}

--solutions--

function isValidIsbn13(str) {
  const digits = str.replace(/-/g, '');
  if (!/^\d{13}$/.test(digits)) return false;
  const sum = digits.split('').reduce((acc, d, i) => acc + d * (i % 2 === 0 ? 1 : 3), 0);
  return sum % 10 === 0;
}