--description--

On October 29, 1971, the first email ever was sent, introducing the username@domain format we still use. Now, there are billions of email addresses.

In this challenge, you are given a list of email addresses and need to sort them alphabetically by domain name first (the part after the @), and username second (the part before the @).

• Sorting should be case-insensitive.
• If more than one email has the same domain, sort them by their username.
• Return an array of the sorted addresses.
• Returned addresses should retain their original case.

For example, given ["[email protected]", "[email protected]", "[email protected]"], return ["[email protected]", "[email protected]", "[email protected]"].

--hints--

sort(["[email protected]", "[email protected]", "[email protected]"]) should return ["[email protected]", "[email protected]", "[email protected]"].

assert.deepEqual(sort(["[email protected]", "[email protected]", "[email protected]"]), ["[email protected]", "[email protected]", "[email protected]"]);

sort(["[email protected]", "[email protected]", "[email protected]"]) should return ["[email protected]", "[email protected]", "[email protected]"].

assert.deepEqual(sort(["[email protected]", "[email protected]", "[email protected]"]), ["[email protected]", "[email protected]", "[email protected]"]);

sort(["[email protected]", "[email protected]", "[email protected]"]) should return ["[email protected]", "[email protected]", "[email protected]"].

assert.deepEqual(sort(["[email protected]", "[email protected]", "[email protected]"]), ["[email protected]", "[email protected]", "[email protected]"]);

sort(["[email protected]", "[email protected]", "[email protected]"]) should return ["[email protected]", "[email protected]", "[email protected]"].

assert.deepEqual(sort(["[email protected]", "[email protected]", "[email protected]"]), ["[email protected]", "[email protected]", "[email protected]"]);

sort(["[email protected]", "[email protected]", "[email protected]", "[email protected]", "[email protected]", "[email protected]"]) should return ["[email protected]", "[email protected]", "[email protected]", "[email protected]", "[email protected]", "[email protected]"].

assert.deepEqual(sort(["[email protected]", "[email protected]", "[email protected]", "[email protected]", "[email protected]", "[email protected]"]), ["[email protected]", "[email protected]", "[email protected]", "[email protected]", "[email protected]", "[email protected]"]);

--seed--

--seed-contents--

function sort(emails) {

  return emails;
}

--solutions--

function sort(emails) {
  return emails.slice().sort((a, b) => {
    const [userA, domainA] = a.split('@');
    const [userB, domainB] = b.split('@');

    const domainCompare = domainA.toLowerCase().localeCompare(domainB.toLowerCase());
    if (domainCompare !== 0) return domainCompare;

    return userA.toLowerCase().localeCompare(userB.toLowerCase());
  });
}