Run results for: Get unique and duplicate emails

Run details:

User agent: Mozilla/5.0 (Windows NT 10.0; Win64; x64) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/112.0.0.0 Safari/537.36

Browser: Chrome 112

Operating system: Windows

Device Platform: Desktop

Date tested: one year ago

Script Preparation code:

emailAddressList = Array.from({length: 1000}, () => `User${Math.floor(Math.random() * 1000)}@emailtesting.com.au`);

Tests:

For Of with has()
const uniqueEmailAddressList = new Set(); const suppressedDuplicateUserEmails = new Set(); for (const email of emailAddressList) { if (uniqueEmailAddressList.has(email)) { suppressedDuplicateUserEmails.add(email); } else { uniqueEmailAddressList.add(email); } }
For Of with size
const uniqueEmailAddressList = new Set(); const duplicateEmails = new Set(); let lastUniqueEmailAddressListSize = 0 for (const email of emailAddressList) { uniqueEmailAddressList.add(email); if (lastUniqueEmailAddressListSize === uniqueEmailAddressList.size) { suppressedDuplicateUserEmails.add(email); lastUniqueEmailAddressListSize += 1 } }
Reduce (current)
const uniqueEmailAddressList = new Set(emailAddressList); const suppressedDuplicateUserEmails = emailAddressList.reduce((list, item, index, array) => { if (array.indexOf(item, index + 1) !== -1 && list.indexOf(item) === -1) { list.push(item); } return list; }, []);