extract_email.js

var testStrings = ['']

// Valid email addresses
testStrings.push('simple@example.com')
testStrings.push('very.common@example.com')
testStrings.push('disposable.style.email.with+symbol@example.com')
testStrings.push('other.email-with-hyphen@example.com')
testStrings.push('fully-qualified-domain@example.com')
testStrings.push('user.name+tag+sorting@example.com (may go to user.name@example.com inbox depending on mail server)')
testStrings.push('x@example.com (one-letter local-part)')
testStrings.push('example-indeed@strange-example.com')
testStrings.push('test/test@test.com (slashes are a printable character, and allowed)')
testStrings.push('admin@mailserver1 (local domain name with no TLD, although ICANN highly discourages dotless email addresses[10])')
testStrings.push('example@s.example (see the List of Internet top-level domains)')
testStrings.push('" "@example.org (space between the quotes)')
testStrings.push('"john..doe"@example.org (quoted double dot)')
testStrings.push('mailhost!username@example.org (bangified host route used for uucp mailers)')
testStrings.push('"very.(),:;<>[]\".VERY.\"very@\\ \"very\".unusual"@strange.example.com (include non-letters character AND multiple at sign, the first one being double quoted)')
testStrings.push('user%example.com@example.org (% escaped mail route to user@example.com via example.org)')
testStrings.push('user-@example.org (local part ending with non-alphanumeric character from the list of allowed printable characters)')
testStrings.push('postmaster@[123.123.123.123] (IP addresses are allowed instead of domains when in square brackets, but strongly discouraged)')
testStrings.push('postmaster@[IPv6:2001:0db8:85a3:0000:0000:8a2e:0370:7334] (IPv6 uses a different syntax)')

// Invalid email addresses
testStrings.push('Invalid: Abc.example.com (no @ character)')
testStrings.push('Invalid: A@b@c@example.com (only one @ is allowed outside quotation marks)')
testStrings.push('Invalid: a"b(c)d,e:f;g<h>i[j\k]l@example.com (none of the special characters in this local-part are allowed outside quotation marks)')
testStrings.push('Invalid: just"not"right@example.com (quoted strings must be dot separated or the only element making up the local-part)')
testStrings.push('Invalid: this is"not\allowed@example.com (spaces, quotes, and backslashes may only exist when within quoted strings and preceded by a backslash)')
testStrings.push('Invalid: this\ still\"not\\allowed@example.com (even if escaped (preceded by a backslash), spaces, quotes, and backslashes must still be contained by quotes)')
testStrings.push('Invalid: 1234567890123456789012345678901234567890123456789012345678901234+x@example.com (local-part is longer than 64 characters)')
testStrings.push('Invalid: i_like_underscore@but_its_not_allowed_in_this_part.example.com (Underscore is not allowed in domain part)')
testStrings.push('Invalid: QA[icon]CHOCOLATE[icon]@test.com (icon characters)')

// Custom tests
testStrings.push('asdf@asdf.de')
testStrings.push('mailto:asdf@asdf.de')
testStrings.push('As Df <asdf@asdf.de>')
testStrings.push('asdf@asdf.de,qwer@qwer.de')
testStrings.push('mailto:asdf@asdf.de,mailto:qwer@qwer.de')
testStrings.push('As Df <asdf@asdf.de>, Qw Er <qwer@qwer.de>')
testStrings.push("\t\n E-Mail:\r\t As Df <asdf@asdf.de> \n\t\rqwer@qwer.de\n\t")
testStrings.push("\t\n E-Mail:\r\t asdf@asdf.de \n\t\rqwer@qwer.de")
testStrings.push("\t\n\rasdf@asdf.de> \n\t\rqwer@qwer.de")
testStrings.push("\t\n\r<asdf@asdf.de qwer@qwer.de")
testStrings.push("\t\n asdf+0123456789@asdf.de")
testStrings.push("\t\n asdf+0123456789@asdf.de+qwer@qwer.de")

for (var i = 0; i < testStrings.length; i++) {
	console.log("-----------------------------\nTest " + (i + 1) + "\nInput: \"" + testStrings[i] + "\"\nOutput: \"" + extractEmail(testStrings[i]) + "\"\n\n")
}

function extractEmail(text) {

    const matches = text.match(/(?:[a-z0-9+!#$%&'*+/=?^_`{|}~-]+(?:\.[a-z0-9!#$%&'*+/=?^_`{|}~-]+)*|"(?:[\x01-\x08\x0b\x0c\x0e-\x1f\x21\x23-\x5b\x5d-\x7f]|\\[\x01-\x09\x0b\x0c\x0e-\x7f])*")@(?:(?:[a-z0-9](?:[a-z0-9-]*[a-z0-9])?\.)+[a-z0-9](?:[a-z0-9-]*[a-z0-9])?|\[(?:(?:25[0-5]|2[0-4][0-9]|[01]?[0-9][0-9]?)\.){3}(?:25[0-5]|2[0-4][0-9]|[01]?[0-9][0-9]?|[a-z0-9-]*[a-z0-9]:(?:[\x01-\x08\x0b\x0c\x0e-\x1f\x21-\x5a\x53-\x7f]|\\[\x01-\x09\x0b\x0c\x0e-\x7f])+)\])/gi)
	
	if (matches && matches.length > 0) {
		return matches[0]
	}
	
	return ""
	
}

/*

-----------------------------
Test 1
Input: ""
Output: ""

-----------------------------
Test 2
Input: "simple@example.com"
Output: "simple@example.com"

-----------------------------
Test 3
Input: "very.common@example.com"
Output: "very.common@example.com"

-----------------------------
Test 4
Input: "disposable.style.email.with+symbol@example.com"
Output: "disposable.style.email.with+symbol@example.com"

-----------------------------
Test 5
Input: "other.email-with-hyphen@example.com"
Output: "other.email-with-hyphen@example.com"

-----------------------------
Test 6
Input: "fully-qualified-domain@example.com"
Output: "fully-qualified-domain@example.com"

-----------------------------
Test 7
Input: "user.name+tag+sorting@example.com (may go to user.name@example.com inbox depending on mail server)"
Output: "user.name+tag+sorting@example.com"

-----------------------------
Test 8
Input: "x@example.com (one-letter local-part)"
Output: "x@example.com"

-----------------------------
Test 9
Input: "example-indeed@strange-example.com"
Output: "example-indeed@strange-example.com"

-----------------------------
Test 10
Input: "test/test@test.com (slashes are a printable character, and allowed)"
Output: "test/test@test.com"

-----------------------------
Test 11
Input: "admin@mailserver1 (local domain name with no TLD, although ICANN highly discourages dotless email addresses[10])"
Output: ""

-----------------------------
Test 12
Input: "example@s.example (see the List of Internet top-level domains)"
Output: "example@s.example"

-----------------------------
Test 13
Input: "" "@example.org (space between the quotes)"
Output: ""

-----------------------------
Test 14
Input: ""john..doe"@example.org (quoted double dot)"
Output: ""john..doe"@example.org"

-----------------------------
Test 15
Input: "mailhost!username@example.org (bangified host route used for uucp mailers)"
Output: "mailhost!username@example.org"

-----------------------------
Test 16
Input: ""very.(),:;<>[]".VERY."very@\ "very".unusual"@strange.example.com (include non-letters character AND multiple at sign, the first one being double quoted)"
Output: "".unusual"@strange.example.com"

-----------------------------
Test 17
Input: "user%example.com@example.org (% escaped mail route to user@example.com via example.org)"
Output: "user%example.com@example.org"

-----------------------------
Test 18
Input: "user-@example.org (local part ending with non-alphanumeric character from the list of allowed printable characters)"
Output: "user-@example.org"

-----------------------------
Test 19
Input: "postmaster@[123.123.123.123] (IP addresses are allowed instead of domains when in square brackets, but strongly discouraged)"
Output: "postmaster@[123.123.123.123]"

-----------------------------
Test 20
Input: "postmaster@[IPv6:2001:0db8:85a3:0000:0000:8a2e:0370:7334] (IPv6 uses a different syntax)"
Output: ""

-----------------------------
Test 21
Input: "Invalid: Abc.example.com (no @ character)"
Output: ""

-----------------------------
Test 22
Input: "Invalid: A@b@c@example.com (only one @ is allowed outside quotation marks)"
Output: "c@example.com"

-----------------------------
Test 23
Input: "Invalid: a"b(c)d,e:f;g<h>i[jk]l@example.com (none of the special characters in this local-part are allowed outside quotation marks)"
Output: "l@example.com"

-----------------------------
Test 24
Input: "Invalid: just"not"right@example.com (quoted strings must be dot separated or the only element making up the local-part)"
Output: "right@example.com"

-----------------------------
Test 25
Input: "Invalid: this is"notallowed@example.com (spaces, quotes, and backslashes may only exist when within quoted strings and preceded by a backslash)"
Output: "notallowed@example.com"

-----------------------------
Test 26
Input: "Invalid: this still"not\allowed@example.com (even if escaped (preceded by a backslash), spaces, quotes, and backslashes must still be contained by quotes)"
Output: "allowed@example.com"

-----------------------------
Test 27
Input: "Invalid: 1234567890123456789012345678901234567890123456789012345678901234+x@example.com (local-part is longer than 64 characters)"
Output: "1234567890123456789012345678901234567890123456789012345678901234+x@example.com"

-----------------------------
Test 28
Input: "Invalid: i_like_underscore@but_its_not_allowed_in_this_part.example.com (Underscore is not allowed in domain part)"
Output: ""

-----------------------------
Test 29
Input: "Invalid: QA[icon]CHOCOLATE[icon]@test.com (icon characters)"
Output: ""

-----------------------------
Test 30
Input: "asdf@asdf.de"
Output: "asdf@asdf.de"

-----------------------------
Test 31
Input: "mailto:asdf@asdf.de"
Output: "asdf@asdf.de"

-----------------------------
Test 32
Input: "As Df <asdf@asdf.de>"
Output: "asdf@asdf.de"

-----------------------------
Test 33
Input: "asdf@asdf.de,qwer@qwer.de"
Output: "asdf@asdf.de"

-----------------------------
Test 34
Input: "mailto:asdf@asdf.de,mailto:qwer@qwer.de"
Output: "asdf@asdf.de"

-----------------------------
Test 35
Input: "As Df <asdf@asdf.de>, Qw Er <qwer@qwer.de>"
Output: "asdf@asdf.de"

-----------------------------
Test 36
Input: "	
 E-Mail:
	 As Df <asdf@asdf.de> 
	
qwer@qwer.de
	"
Output: "asdf@asdf.de"

-----------------------------
Test 37
Input: "	
 E-Mail:
	 asdf@asdf.de 
	
qwer@qwer.de"
Output: "asdf@asdf.de"

-----------------------------
Test 38
Input: "	

asdf@asdf.de> 
	
qwer@qwer.de"
Output: "asdf@asdf.de"

-----------------------------
Test 39
Input: "	

<asdf@asdf.de qwer@qwer.de"
Output: "asdf@asdf.de"

-----------------------------
Test 40
Input: "	
 asdf+0123456789@asdf.de"
Output: "asdf+0123456789@asdf.de"

-----------------------------
Test 41
Input: "	
 asdf+0123456789@asdf.de+qwer@qwer.de"
Output: "asdf+0123456789@asdf.de"

*/