Algorithm for Sorting Duplicate Items

email_helper.js

export const filterEmails = emails => {
  let resultsMap = {};
  let results    = []

  for (let i = 0; i < emails.length; i++) {
    let email = emails[i].toLowerCase();

    if (!resultsMap[email]) {
      resultsMap[email] = true
      results.push(email)
    }
  }

  return results;
}