Email Validator Regex

regex.js

function isEmail (str) {
  return str ? /^(([^<>()\[\]\.,;:\s@\"]+(\.[^<>()\[\]\.,;:\s@\"]+)*)|(\".+\"))@(([^<>()[\]\.,;:\s@\"]+\.)+[^<>()[\]\.,;:\s@\"]{2,})$/.test(str) : false
}

const test = require('ava')
const sinon = require('sinon')

test('validate#isEmail returns true if unicode emails', t => {
  t.true(isEmail('💩+तфâ.πüñó1@ӕ.昭字'))
})

test('validate#isEmail returns true no matter the length of the email', t => {
  t.true(isEmail('the-total-length@of-an-entire-address.cannot-be-longer-than-two-hundred-and-fifty-four-characters.and-this-address-is-255-characters-exactly.so-it-should-be-invalid.and-im-going-to-add-some-more-words-here.to-increase-the-length-blah-blah-blah-blah-bl.org'))
})

test('validate#isEmail returns false if email is blank', t => {
  t.false(isEmail(''))
  t.false(isEmail(' '))
})

test('validate#isEmail returns false if no . in TLD', t => {
  t.false(isEmail('foo@bar'))
  t.false(isEmail('f.oo@bar'))
})

test('validate#isEmail returns false if less or more than one @', t => {
  t.false(isEmail('invalid'))
  t.false(isEmail('invalid@[email protected]'))
})

test('validate#isEmail returns false only for certain special characters', t => {
  t.false(isEmail('<>()[],;:"@email.com'))
  t.true(isEmail("!#!$%&'*+-./\=?^_`{}|[email protected]"))
  t.false(isEmail('[email protected]'))
  t.false(isEmail("partially.\"quoted\"@sld.com"))
  t.false(isEmail('a      b   [email protected]'))
})

test('validate#isEmail returns false if TLDs shorter than 2 characters', t => {
  t.false(isEmail('[email protected]'))
  t.false(isEmail('[email protected].'))
})