Clean javascript 4 lines solution without Regex
js\nvar numUniqueEmails = function(emails) {\n  return (new Set(emails.map(email => {\n    const [local, domain] = email.split(\'@\');\n    return local.split(\
```js\nvar numUniqueEmails = function(emails) {\n  return (new Set(emails.map(email => {\n    const [local, domain] = email.split(\'@\');\n    return local.split(\'+\').shift().split(\'.\').join(\'\') + \'@\' + domain;\n  }))).size;\n};\n```
['JavaScript']