Develop Reference

Why is the regex "\d+(-\d+)?[A-Z]?" not matching the string "180-186" in a HTML5 pattern attribute?

I have the following HTML5 form:
<form id="address-form" method="POST">
// ...other inputs that work fine
<input type="text" name="street_number" class="form-control" placeholder="Street No.*" tabindex="3" required pattern="\d+(-\d+)?[A-Z]?" title="Please enter only digits separated by a single optional hyphen, with a single optional letter suffix.">
<input type="text" name="street_address" class="form-control" placeholder="Address*" tabindex="4" required pattern="[A-z ]+" title="Please enter only letters and spaces.">
// ...other inputs that work fine
</form>
And the following jQuery:
let form = $('#address-form');
form.find('[required]').each((i, elem) => {
invalidElem = $(elem);
// ...more unrelated code
if (elem.name === 'password1' && elem.value !== '') {
password = elem.value;
}
if (elem.name === 'password2') {
elem.setCustomValidity(elem.value === password ? '' :
'This field must match the password field.');
}
invalidElem.removeAttr('style');
return (isValid = elem.reportValidity());
});
I am testing validation of the first input shown with the string "180-186" and it is failing. Why?
According to https://regex101.com/ this should work fine in JavaScript, which I assume is the regex engine used by browsers to validate pattern attributes...but Chrome (at least) seems to disprove that assumption, so if anyone definitively knows the actual regex engine used by browsers I'd love to know.
In case it's not obvious to anyone, this input needs to take the street number portion of an address. So "143", "22A", "180-186" and "1-7A" should all match, but having the letter anywhere but the end should not match, nor should anything with multiple hyphens, letters or any spaces.
I'd also accept any answer that suggests a reasonable compromise to my strict definition of a house or building number.

It turns out that VS Code had simply turned my hyphen into an em dash when I was typing static values into the HTML...d'oh!
Anyway thanks to everyone who commented for trying to help :-)

How can i check if an email is valid [duplicate]

This question's answers are a community effort. Edit existing answers to improve this post. It is not currently accepting new answers or interactions.
I'd like to check if the user input is an email address in JavaScript, before sending it to a server or attempting to send an email to it, to prevent the most basic mistyping. How could I achieve this?

Using regular expressions is probably the best way. You can see a bunch of tests here (taken from chromium)
const validateEmail = (email) => {
return String(email)
.toLowerCase()
.match(
/^(([^<>()[\]\\.,;:\s#"]+(\.[^<>()[\]\\.,;:\s#"]+)*)|(".+"))#((\[[0-9]{1,3}\.[0-9]{1,3}\.[0-9]{1,3}\.[0-9]{1,3}\])|(([a-zA-Z\-0-9]+\.)+[a-zA-Z]{2,}))$/
);
};
Here's the example of a regular expression that accepts unicode:
const re =
/^(([^<>()[\]\.,;:\s#\"]+(\.[^<>()[\]\.,;:\s#\"]+)*)|(\".+\"))#(([^<>()[\]\.,;:\s#\"]+\.)+[^<>()[\]\.,;:\s#\"]{2,})$/i;
But keep in mind that one should not rely only upon JavaScript validation. JavaScript can easily be disabled. This should be validated on the server side as well.
Here's an example of the above in action:
const validateEmail = (email) => {
return email.match(
/^(([^<>()[\]\\.,;:\s#\"]+(\.[^<>()[\]\\.,;:\s#\"]+)*)|(\".+\"))#((\[[0-9]{1,3}\.[0-9]{1,3}\.[0-9]{1,3}\.[0-9]{1,3}\])|(([a-zA-Z\-0-9]+\.)+[a-zA-Z]{2,}))$/
);
};
const validate = () => {
const $result = $('#result');
const email = $('#email').val();
$result.text('');
if (validateEmail(email)) {
$result.text(email + ' is valid :)');
$result.css('color', 'green');
} else {
$result.text(email + ' is not valid :(');
$result.css('color', 'red');
}
return false;
}
$('#email').on('input', validate);
<script src="https://ajax.googleapis.com/ajax/libs/jquery/2.1.1/jquery.min.js"></script>
<label for="email">Enter an email address: </label>
<input id="email" />
<h2 id="result"></h2>

I've slightly modified Jaymon's answer for people who want really simple validation in the form of:
anystring#anystring.anystring
The regular expression:
/^\S+#\S+\.\S+$/
To prevent matching multiple # signs:
/^[^\s#]+#[^\s#]+\.[^\s#]+$/
The above regexes match the whole string, remove the leading and ^ and trailing $ if you want to match anywhere in the string. The example below matches anywhere in the string.
If you do want to match the whole sring, you may want to trim() the string first.
Example JavaScript function:
function validateEmail(email) {
var re = /\S+#\S+\.\S+/;
return re.test(email);
}
console.log(validateEmail('my email is anystring#anystring.any')); // true
console.log(validateEmail('my email is anystring#anystring .any')); // false

Just for completeness, here you have another RFC 2822 compliant regex
The official standard is known as RFC 2822. It describes the syntax that valid email addresses must adhere to. You can (but you shouldn't — read on) implement it with this regular expression:
(?:[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])?|\[(?:(?:25[0-5]|2[0-4][0-9]|[01]?[0-9][0-9]?)\.){3}(?:25[0-5]|2[0-4][0-9]|[01]?[0-9][0-9]?|[a-z0-9-]*[a-z0-9]:(?:[\x01-\x08\x0b\x0c\x0e-\x1f\x21-\x5a\x53-\x7f]|\\[\x01-\x09\x0b\x0c\x0e-\x7f])+)\])
(...) We get a more practical implementation of RFC 2822 if we omit the syntax using double quotes and square brackets. It will still match 99.99% of all email addresses in actual use today.
[a-z0-9!#$%&'*+/=?^_`{|}~-]+(?:\.[a-z0-9!#$%&'*+/=?^_`{|}~-]+)*#(?:[a-z0-9](?:[a-z0-9-]*[a-z0-9])?\.)+[a-z0-9](?:[a-z0-9-]*[a-z0-9])?
A further change you could make is to allow any two-letter country code top level domain, and only specific generic top level domains. This regex filters dummy email addresses like asdf#adsf.adsf. You will need to update it as new top-level domains are added.
[a-z0-9!#$%&'*+/=?^_`{|}~-]+(?:\.[a-z0-9!#$%&'*+/=?^_`{|}~-]+)*#(?:[a-z0-9](?:[a-z0-9-]*[a-z0-9])?\.)+(?:[A-Z]{2}|com|org|net|gov|mil|biz|info|mobi|name|aero|jobs|museum)\b
So even when following official standards, there are still trade-offs to be made. Don't blindly copy regular expressions from online libraries or discussion forums. Always test them on your own data and with your own applications.
Emphasis mine

Wow, there are lots of complexity here. If all you want to do is just catch the most obvious syntax errors, I would do something like this:
^\S+#\S+$
It usually catches the most obvious errors that the user makes and assures that the form is mostly right, which is what JavaScript validation is all about.
EDIT:
We can also check for '.' in the email using
/^\S+#\S+\.\S+$/

There's something you have to understand the second you decide to use a regular expression to validate emails: It's probably not a good idea. Once you have come to terms with that, there are many implementations out there that can get you halfway there, this article sums them up nicely.
In short, however, the only way to be absolutely, positively sure that what the user entered is in fact an email is to actually send an email and see what happens. Other than that it's all just guesses.

HTML5 itself has email validation. If your browser supports HTML5 then you can use the following code.
<form>
<label>Email Address
<input type="email" placeholder="me#example.com" required>
</label>
<input type="submit">
</form>
jsFiddle link
From the HTML5 spec:
A valid e-mail address is a string that matches the email production of the following ABNF, the character set for which is Unicode.
email = 1*( atext / "." ) "#" label *( "." label )
label = let-dig [ [ ldh-str ] let-dig ] ; limited to a length of 63 characters by RFC 1034 section 3.5
atext = < as defined in RFC 5322 section 3.2.3 >
let-dig = < as defined in RFC 1034 section 3.5 >
ldh-str = < as defined in RFC 1034 section 3.5 >
This requirement is a willful violation of RFC 5322, which defines a syntax for e-mail addresses that is simultaneously too strict (before the "#" character), too vague (after the "#" character), and too lax (allowing comments, whitespace characters, and quoted strings in manners unfamiliar to most users) to be of practical use here.
The following JavaScript- and Perl-compatible regular expression is an implementation of the above definition.
/^[a-zA-Z0-9.!#$%&'*+\/=?^_`{|}~-]+#[a-zA-Z0-9](?:[a-zA-Z0-9-]{0,61}[a-zA-Z0-9])?(?:\.[a-zA-Z0-9](?:[a-zA-Z0-9-]{0,61}[a-zA-Z0-9])?)*$/

I have found this to be the best solution:
/^[^\s#]+#[^\s#]+\.[^\s#]+$/
It allows the following formats:
1. prettyandsimple#example.com
2. very.common#example.com
3. disposable.style.email.with+symbol#example.com
4. other.email-with-dash#example.com
9. #!$%&'*+-/=?^_`{}|~#example.org
6. "()[]:,;#\\\"!#$%&'*+-/=?^_`{}| ~.a"#example.org
7. " "#example.org (space between the quotes)
8. üñîçøðé#example.com (Unicode characters in local part)
9. üñîçøðé#üñîçøðé.com (Unicode characters in domain part)
10. Pelé#example.com (Latin)
11. δοκιμή#παράδειγμα.δοκιμή (Greek)
12. 我買#屋企.香港 (Chinese)
13. 甲斐#黒川.日本 (Japanese)
14. чебурашка#ящик-с-апельсинами.рф (Cyrillic)
It's clearly versatile and allows the all-important international characters, while still enforcing the basic anything#anything.anything format. It will block spaces which are technically allowed by RFC, but they are so rare that I'm happy to do this.

In modern browsers you can build on top of #Sushil's answer with pure JavaScript and the DOM:
function validateEmail(value) {
var input = document.createElement('input');
input.type = 'email';
input.required = true;
input.value = value;
return typeof input.checkValidity === 'function' ? input.checkValidity() : /\S+#\S+\.\S+/.test(value);
}
I've put together an example in the fiddle http://jsfiddle.net/boldewyn/2b6d5/. Combined with feature detection and the bare-bones validation from Squirtle's Answer, it frees you from the regular expression massacre and does not bork on old browsers.

JavaScript can match a regular expression:
emailAddress.match( / some_regex /);
Here's an RFC22 regular expression for emails:
^((?>[a-zA-Z\d!#$%&'*+\-/=?^_`{|}~]+\x20*|"((?=[\x01-\x7f])[^"\\]|\\[\x01-\x7f])*
"\x20*)*(?<angle><))?((?!\.)(?>\.?[a-zA-Z\d!#$%&'*+\-/=?^_`{|}~]+)+|"((?=[\x01-\x
7f])[^"\\]|\\[\x01-\x7f])*")#(((?!-)[a-zA-Z\d\-]+(?<!-)\.)+[a-zA-Z]{2,}|\[(((?(?<
!\[)\.)(25[0-5]|2[0-4]\d|[01]?\d?\d)){4}|[a-zA-Z\d\-]*[a-zA-Z\d]:((?=[\x01-\x7f])
[^\\\[\]]|\\[\x01-\x7f])+)\])(?(angle)>)$

All email addresses contain an 'at' (i.e. #) symbol. Test that necessary condition:
email.includes('#')
Or, if you need to support IE/older browsers:
email.indexOf('#') > 0
Don't bother with anything more complicated. Even if you could perfectly determine whether an email is RFC-syntactically valid, that wouldn't tell you whether it belongs to the person who supplied it. That's what really matters.
To test that, send a validation message.

Correct validation of email address in compliance with the RFCs is not something that can be achieved with a one-liner regular expression. An article with the best solution I've found in PHP is What is a valid email address?. Obviously, it has been ported to Java. I think the function is too complex to be ported and used in JavaScript. JavaScript/node.js port: https://www.npmjs.com/package/email-addresses.
A good practice is to validate your data on the client, but double-check the validation on the server. With this in mind, you can simply check whether a string looks like a valid email address on the client and perform the strict check on the server.
Here's the JavaScript function I use to check if a string looks like a valid mail address:
function looksLikeMail(str) {
var lastAtPos = str.lastIndexOf('#');
var lastDotPos = str.lastIndexOf('.');
return (lastAtPos < lastDotPos && lastAtPos > 0 && str.indexOf('##') == -1 && lastDotPos > 2 && (str.length - lastDotPos) > 2);
}
Explanation:
lastAtPos < lastDotPos: Last # should be before last . since # cannot be part of server name (as far as I know).
lastAtPos > 0: There should be something (the email username) before the last #.
str.indexOf('##') == -1: There should be no ## in the address. Even if # appears as the last character in email username, it has to be quoted so " would be between that # and the last # in the address.
lastDotPos > 2: There should be at least three characters before the last dot, for example a#b.com.
(str.length - lastDotPos) > 2: There should be enough characters after the last dot to form a two-character domain. I'm not sure if the brackets are necessary.

This is the correct RFC822 version.
function checkEmail(emailAddress) {
var sQtext = '[^\\x0d\\x22\\x5c\\x80-\\xff]';
var sDtext = '[^\\x0d\\x5b-\\x5d\\x80-\\xff]';
var sAtom = '[^\\x00-\\x20\\x22\\x28\\x29\\x2c\\x2e\\x3a-\\x3c\\x3e\\x40\\x5b-\\x5d\\x7f-\\xff]+';
var sQuotedPair = '\\x5c[\\x00-\\x7f]';
var sDomainLiteral = '\\x5b(' + sDtext + '|' + sQuotedPair + ')*\\x5d';
var sQuotedString = '\\x22(' + sQtext + '|' + sQuotedPair + ')*\\x22';
var sDomain_ref = sAtom;
var sSubDomain = '(' + sDomain_ref + '|' + sDomainLiteral + ')';
var sWord = '(' + sAtom + '|' + sQuotedString + ')';
var sDomain = sSubDomain + '(\\x2e' + sSubDomain + ')*';
var sLocalPart = sWord + '(\\x2e' + sWord + ')*';
var sAddrSpec = sLocalPart + '\\x40' + sDomain; // complete RFC822 email address spec
var sValidEmail = '^' + sAddrSpec + '$'; // as whole string
var reValidEmail = new RegExp(sValidEmail);
return reValidEmail.test(emailAddress);
}

This was stolen from http://codesnippets.joyent.com/posts/show/1917
email = $('email');
filter = /^([a-zA-Z0-9_\.\-])+\#(([a-zA-Z0-9\-])+\.)+([a-zA-Z0-9]{2,4})+$/;
if (filter.test(email.value)) {
// Yay! valid
return true;
}
else
{return false;}

Do this:
^([a-zA-Z0-9!#$%&'*+\/=?^_`{|}~-]+(?:\.[a-zA-Z0-9!#$%&'*+\/=?^_`{|}~-]+)*#(?:[a-zA-Z0-9](?:[a-zA-Z0-9-]*[a-zA-Z0-9])?\.)+[a-zA-Z0-9](?:[a-zA-Z0-9-]*[a-zA-Z0-9])?)$
It's based on RFC 2822
Test it at https://regex101.com/r/857lzc/1
Often when storing email addresses in the database I make them lowercase and, in practice, regexs can usually be marked case insensitive. In those cases this is slightly shorter:
[a-z0-9!#$%&'*+/=?^_`{|}~-]+(?:\.[a-z0-9!#$%&'*+/=?^_`{|}~-]+)*#(?:[a-z0-9](?:[a-z0-9-]*[a-z0-9])?\.)+[a-z0-9](?:[a-z0-9-]*[a-z0-9])?
Here's an example of it being used in JavaScript (with the case insensitive flag i at the end).
var emailCheck=/^[a-z0-9!#$%&'*+/=?^_`{|}~-]+(?:\.[a-z0-9!#$%&'*+/=?^_`{|}~-]+)*#(?:[a-z0-9](?:[a-z0-9-]*[a-z0-9])?\.)+[a-z0-9](?:[a-z0-9-]*[a-z0-9])?$/i;
console.log( emailCheck.test('some.body#domain.co.uk') );
Note:
Technically some emails can include quotes in the section before the # symbol with escape characters inside the quotes (so your email user can be obnoxious and contain stuff like # and "..." as long as it's written in quotes). NOBODY DOES THIS EVER! It's obsolete. But, it IS included in the true RFC 2822 standard and omitted here.
Note 2:
The beginning of an email (before the # sign) can be case sensitive (via the spec). However, anyone with a case-sensitive email is probably used to having issues, and, in practice, case insensitive is a safe assumption. More info: Are email addresses case sensitive?
More info: http://www.regular-expressions.info/email.html

I'm really looking forward to solve this problem.
So I modified email validation regular expression above
Original
/^(([^<>()\[\]\\.,;:\s#"]+(\.[^<>()\[\]\\.,;:\s#"]+)*)|(".+"))#((\[[0-9]{1,3}\.[0-9]{1,3}\.[0-9]{1,3}\.[0-9]{1,3}])|(([a-zA-Z\-0-9]+\.)+[a-zA-Z]{2,}))$/
Modified
/^(([^<>()\[\]\.,;:\s#\"]+(\.[^<>()\[\]\.,;:\s#\"]+)*)|(\".+\"))#(([^<>()\.,;\s#\"]+\.{0,1})+[^<>()\.,;:\s#\"]{2,})$/
to pass the examples in Wikipedia Email Address.
And you can see the result in here.

Simply check out if the entered email address is valid or not using HTML.
<input type="email"/>
There isn't any need to write a function for validation.

You should not use regular expressions to validate an input string to check if it's an email. It's too complicated and would not cover all the cases.
Now since you can only cover 90% of the cases, write something like:
function isPossiblyValidEmail(txt) {
return txt.length > 5 && txt.indexOf('#')>0;
}
You can refine it. For instance, 'aaa#' is valid. But overall you get the gist. And don't get carried away... A simple 90% solution is better than 100% solution that does not work.
The world needs simpler code...

Wikipedia standard mail syntax :
https://en.wikipedia.org/wiki/Email_address#Examples
https://fr.wikipedia.org/wiki/Adresse_%C3%A9lectronique#Syntaxe_exacte
Function :
function validMail(mail)
{
return /^(([^<>()\[\]\.,;:\s#\"]+(\.[^<>()\[\]\.,;:\s#\"]+)*)|(\".+\"))#(([^<>()\.,;\s#\"]+\.{0,1})+([^<>()\.,;:\s#\"]{2,}|[\d\.]+))$/.test(mail);
}
Valid emails :
validMail('Abc#example.com') // Return true
validMail('Abc#example.com.') // Return true
validMail('Abc#10.42.0.1') // Return true
validMail('user#localserver') // Return true
validMail('Abc.123#example.com') // Return true
validMail('user+mailbox/department=shipping#example.com') // Return true
validMail('"very.(),:;<>[]\".VERY.\"very#\\ \"very\".unusual"#strange.example.com') // Return true
validMail('!#$%&\'*+-/=?^_`.{|}~#example.com') // Return true
validMail('"()<>[]:,;#\\\"!#$%&\'-/=?^_`{}| ~.a"#example.org') // Return true
validMail('"Abc#def"#example.com') // Return true
validMail('"Fred Bloggs"#example.com') // Return true
validMail('"Joe.\\Blow"#example.com') // Return true
validMail('Loïc.Accentué#voilà.fr') // Return true
validMail('" "#example.org') // Return true
validMail('user#[IPv6:2001:DB8::1]') // Return true
Invalid emails :
validMail('Abc.example.com') // Return false
validMail('A#b#c#example.com') // Return false
validMail('a"b(c)d,e:f;g<h>i[j\k]l#example.com') // Return false
validMail('just"not"right#example.com') // Return false
validMail('this is"not\allowed#example.com') // Return false
validMail('this\ still\"not\\allowed#example.com') // Return false
validMail('john..doe#example.com') // Return false
validMail('john.doe#example..com') // Return false
Show this test : https://regex101.com/r/LHJ9gU/1

Regex updated! try this
let val = 'email#domain.com';
if(/^[a-z0-9][a-z0-9-_\.]+#([a-z]|[a-z0-9]?[a-z0-9-]+[a-z0-9])\.[a-z0-9]{2,10}(?:\.[a-z]{2,10})?$/.test(val)) {
console.log('passed');
}
typscript version complete
//
export const emailValid = (val:string):boolean => /^[a-z0-9][a-z0-9-_\.]+#([a-z]|[a-z0-9]?[a-z0-9-]+[a-z0-9])\.[a-z0-9]{2,10}(?:\.[a-z]{2,10})?$/.test(val);
more info https://git.io/vhEfc

It's hard to get an email validator 100% correct. The only real way to get it correct would be to send a test email to the account. That said, there are a few basic checks that can help make sure that you're getting something reasonable.
Some things to improve:
Instead of new RegExp, just try writing the regexp out like this:
if (reg.test(/#/))
Second, check to make sure that a period comes after the # sign, and make sure that there are characters between the #s and periods.

This is how node-validator does it:
/^(?:[\w\!\#\$\%\&\'\*\+\-\/\=\?\^\`\{\|\}\~]+\.)*[\w\!\#\$\%\&\'\*\+\-\/\=\?\^\`\{\|\}\~]+#(?:(?:(?:[a-zA-Z0-9](?:[a-zA-Z0-9\-](?!\.)){0,61}[a-zA-Z0-9]?\.)+[a-zA-Z0-9](?:[a-zA-Z0-9\-](?!$)){0,61}[a-zA-Z0-9]?)|(?:\[(?:(?:[01]?\d{1,2}|2[0-4]\d|25[0-5])\.){3}(?:[01]?\d{1,2}|2[0-4]\d|25[0-5])\]))$/

A solution that does not check the existence of the TLD is incomplete.
Almost all answers to this questions suggest using Regex to validate emails addresses. I think Regex is only good for a rudimentary validation. It seems that the checking validation of email addresses is actually two separate problems:
1- Validation of email format: Making sure if the email complies with the format and pattern of emails in RFC 5322 and if the TLD actually exists. A list of all valid TLDs can be found here.
For example, although the address example#example.ccc will pass the regex, it is not a valid email, because ccc is not a top-level domain by IANA.
2- Making sure the email actually exists: For doing this, the only option is to send the users an email.

Use this code inside your validator function:
var emailID = document.forms["formName"]["form element id"].value;
atpos = emailID.indexOf("#");
dotpos = emailID.lastIndexOf(".");
if (atpos < 1 || ( dotpos - atpos < 2 ))
{
alert("Please enter correct email ID")
return false;
}
Else you can use jQuery. Inside rules define:
eMailId: {
required: true,
email: true
}

In contrast to squirtle, here is a complex solution, but it does a mighty fine job of validating emails properly:
function isEmail(email) {
return /^((([a-z]|\d|[!#\$%&'\*\+\-\/=\?\^_`{\|}~]|[\u00A0-\uD7FF\uF900-\uFDCF\uFDF0-\uFFEF])+(\.([a-z]|\d|[!#\$%&'\*\+\-\/=\?\^_`{\|}~]|[\u00A0-\uD7FF\uF900-\uFDCF\uFDF0-\uFFEF])+)*)|((\x22)((((\x20|\x09)*(\x0d\x0a))?(\x20|\x09)+)?(([\x01-\x08\x0b\x0c\x0e-\x1f\x7f]|\x21|[\x23-\x5b]|[\x5d-\x7e]|[\u00A0-\uD7FF\uF900-\uFDCF\uFDF0-\uFFEF])|(\\([\x01-\x09\x0b\x0c\x0d-\x7f]|[\u00A0-\uD7FF\uF900-\uFDCF\uFDF0-\uFFEF]))))*(((\x20|\x09)*(\x0d\x0a))?(\x20|\x09)+)?(\x22)))#((([a-z]|\d|[\u00A0-\uD7FF\uF900-\uFDCF\uFDF0-\uFFEF])|(([a-z]|\d|[\u00A0-\uD7FF\uF900-\uFDCF\uFDF0-\uFFEF])([a-z]|\d|-|\.|_|~|[\u00A0-\uD7FF\uF900-\uFDCF\uFDF0-\uFFEF])*([a-z]|\d|[\u00A0-\uD7FF\uF900-\uFDCF\uFDF0-\uFFEF])))\.)+(([a-z]|[\u00A0-\uD7FF\uF900-\uFDCF\uFDF0-\uFFEF])|(([a-z]|[\u00A0-\uD7FF\uF900-\uFDCF\uFDF0-\uFFEF])([a-z]|\d|-|\.|_|~|[\u00A0-\uD7FF\uF900-\uFDCF\uFDF0-\uFFEF])*([a-z]|[\u00A0-\uD7FF\uF900-\uFDCF\uFDF0-\uFFEF])))$/i.test(email);
}
Use like so:
if (isEmail('youremail#yourdomain.com')){ console.log('This is email is valid'); }

var testresults
function checkemail() {
var str = document.validation.emailcheck.value
var filter = /^([\w-]+(?:\.[\w-]+)*)#((?:[\w-]+\.)*\w[\w-]{0,66})\.([a-z]{2,6}(?:\.[a-z]{2})?)$/i
if (filter.test(str))
testresults = true
else {
alert("Please input a valid email address!")
testresults = false
}
return (testresults)
}
function checkbae() {
if (document.layers || document.getElementById || document.all)
return checkemail()
else
return true
}
<form name="validation" onSubmit="return checkbae()">
Please input a valid email address:<br />
<input type="text" size=18 name="emailcheck">
<input type="submit" value="Submit">
</form>

My knowledge of regular expressions is not that good. That's why I check the general syntax with a simple regular expression first and check more specific options with other functions afterwards. This may not be not the best technical solution, but this way I'm way more flexible and faster.
The most common errors I've come across are spaces (especially at the beginning and end) and occasionally a double dot.
function check_email(val){
if(!val.match(/\S+#\S+\.\S+/)){ // Jaymon's / Squirtle's solution
// Do something
return false;
}
if( val.indexOf(' ')!=-1 || val.indexOf('..')!=-1){
// Do something
return false;
}
return true;
}
check_email('check#thiscom'); // Returns false
check_email('check#this..com'); // Returns false
check_email(' check#this.com'); // Returns false
check_email('check#this.com'); // Returns true

Regex for validating email address
[a-z0-9!#$%&'*+/=?^_`{|}~-]+(?:\.[a-z0-9!#$%&'*+/=?^_`{|}~-]+)*#(?:[a-z0-9](?:[a-z0-9-]*[a-z0-9])?\.)+[a-z0-9](?:[a-z0-9-]*[a-z0-9])+

Here is a very good discussion about using regular expressions to validate email addresses; "Comparing E-mail Address Validating Regular Expressions"
Here is the current top expression, that is JavaScript compatible, for reference purposes:
/^[-a-z0-9~!$%^&*_=+}{\'?]+(\.[-a-z0-9~!$%^&*_=+}{\'?]+)*#([a-z0-9_][-a-z0-9_]*(\.[-a-z0-9_]+)*\.(aero|arpa|biz|com|coop|edu|gov|info|int|mil|museum|name|net|org|pro|travel|mobi|[a-z][a-z])|([0-9]{1,3}\.[0-9]{1,3}\.[0-9]{1,3}\.[0-9]{1,3}))(:[0-9]{1,5})?$/i

Apparently, that's it:
/^([\w\!\#$\%\&\'\*\+\-\/\=\?\^\`{\|\}\~]+\.)*[\w\!\#$\%\&\'\*\+\-\/\=\?\^\`{\|\}\~]+#((((([a-z0-9]{1}[a-z0-9\-]{0,62}[a-z0-9]{1})|[a-z])\.)+[a-z]{2,6})|(\d{1,3}\.){3}\d{1,3}(\:\d{1,5})?)$/i
Taken from http://fightingforalostcause.net/misc/2006/compare-email-regex.php on Oct 1 '10.
But, of course, that's ignoring internationalization.

I was looking for a Regex in JS that passes all Email Address test cases:
email#example.com Valid email
firstname.lastname#example.com Email contains dot in the address field
email#subdomain.example.com Email contains dot with subdomain
firstname+lastname#example.com Plus sign is considered valid character
email#192.0.2.123 Domain is valid IP address
email#[192.0.2.123] Square bracket around IP address is considered valid
“email”#example.com Quotes around email is considered valid
1234567890#example.com Digits in address are valid
email#domain-one.example Dash in domain name is valid
_______#example.com Underscore in the address field is valid
email#example.name .name is valid Top Level Domain name
email#example.co.jp Dot in Top Level Domain name also considered valid (using co.jp as example here)
firstname-lastname#example.com Dash in address field is valid
Here we go :
http://regexr.com/3f07j
OR regex:
Regex = /(([^<>()\[\]\\.,;:\s#"]+(\.[^<>()\[\]\\.,;:\s#"]+)*)|(".+"))#[*[a-zA-Z0-9-]+.[a-zA-Z0-9-.]+]*/

javascript validation not working for only alphabetic values

I have used a javascript validation function to validate it. I've used it to see whether the text entered to the html textbox is alphabetic(No numeric characters allowed). The function is called during onkeyup and onblur. The only problem is even when numeric values or special characters are typed in the validation doesn't work. If I leave the field blank then it works(Displays that the field is left blank). Here's my javascript code:
function isAlphabetic(x,y){
var exp = /^[a-zA-Z]+$/;
var a = document.getElementById(y).value;
if(a=="" || a== null){
document.getElementById(x).innerHTML = "You cannot leave this feild empty";
return;
}
else if(a!="" && a!= null){
if(y.match(exp)){
document.getElementById(x).innerHTML = "";
return;
}
else{
document.getElementById(x).innerHTML = "Only enter alphabetic characters allowed";
return;
}
}
else{
return;
}

If you use y as an id of element, I suppose you shouldn't check it with your regexp. Instead you should check a:
if(a.match(exp)) {

You don't need JavaScript anymore for any of this. Use the pattern attribute on the input field and the browser won't let the user enter anything that doesn't match, and use required to prevent submitting the form with an empty value.
Also, do you really want only ASCII letters? (are spaces allowed? how about non-ASCII letters such as "é"?)

Form validation of numeric characters in JavaScript

I would like to perform form validation using JavaScript to check for input field only to contain numeric characters.So far, the validation checks for the field not being empty - which works fine.However, numeric characters validation is not working.I would be grateful for any help.Many thanks.
<script type="text/javascript">
//form validation
function validateForm()
{
var x=document.forms["cdp_form"]["univer_number"].value
if (x==null || x=="")
{
alert("University number (URN) field must be filled in");
cdp_form.univer_number.focus();
return false;
}
else if (is_valid = /^[0-9]+$/.test(x))
{
alert("University number (URN) field must have numeric characters");
cdp_form.univer_number.focus();
return false;
}
}
</script>
<input type ="text" id="univer_number" maxlength="7" size="25" name="univer_number" />

Rather than using Regex, if it must only be numerals you can simply use IsNumeric in Javascript.
IsNumeric('1') => true;
IsNumeric('145266') => true;
IsNumeric('abc5423856') => false;

You need invert your regular expression (add ^ inside [0-9]):
/^[^0-9]+$/

Your test condition is a bit strange:
else if (is_valid = /^[0-9]+$/.test(x))
Why have the redundant comparison to is_valid? Just do:
else if (/^[0-9]+$/.test(x))
Though the regex you are using will match numerals and only numerals - you need to change it to match anything that is not a numeral - like this /^[^0-9]+$/.
Better yet, get rid of the regex altogether and use IsNumeric:
else if (!IsNumeric(x))

On your line that says else if (is_valid = /^[0-9]+$/.test(x)), you're doing a simple assignment instead of testing that it is actually matching the regex.

Your pattern will still accept this input <b>##$##123 or ad!##12<b>. Use this pattern I created:
/[a-zA-Z-!##$%^&*()_+\=\[\]{};':"\\|,.<>\/?]/
This pattern will check if it is alphabetic and special characters.

You need to test for the negation of the RegExp because you want the validation to alert upon failure, so just add ! in front of it:
else if (is_valid = !/^[0-9]+$/.test(x))
See example →

I know this is an old post but I thought I'd post what worked for me. I don't require the field to be filled at all but if it is it has to be numerical:
function validateForm()
{
var x=document.forms["myformName"]["myformField"].value;
if (/[^0-9]+$/.test(x))
{
alert("Please enter a numerical amount without a decimal point");
myformName.myformField.focus();
return false;
}
}

JavaScript Regular Expression Email Validation [duplicate]

This question already has answers here:
How can I validate an email address in JavaScript?
(79 answers)
How can I validate an email address using a regular expression?
(79 answers)
Closed 8 years ago.
This code is always alerting out "null", which means that the string does not match the expression.
var pattern = "^\w+#[a-zA-Z_]+?\.[a-zA-Z]{2,3}$";
function isEmailAddress(str) {
str = "azamsharp#gmail.com";
alert(str.match(pattern));
return str.match(pattern);
}

If you define your regular expression as a string then all backslashes need to be escaped, so instead of '\w' you should have '\\w'.
Alternatively, define it as a regular expression:
var pattern = /^\w+#[a-zA-Z_]+?\.[a-zA-Z]{2,3}$/;
BTW, please don't validate email addresses on the client-side. Your regular expression is way too simple to pass for a solid implementation anyway.
See the real thing here: http://www.ex-parrot.com/~pdw/Mail-RFC822-Address.html

this is the one i am using on my page.
http://www.zparacha.com/validate-email-address-using-javascript-regular-expression/
/^[a-zA-Z0-9._-]+#[a-zA-Z0-9.-]+\.[a-zA-Z]{2,6}$/

I've been using this function for a while. it returns a boolean value.
// Validates email address of course.
function validEmail(e) {
var filter = /^\s*[\w\-\+_]+(\.[\w\-\+_]+)*\#[\w\-\+_]+\.[\w\-\+_]+(\.[\w\-\+_]+)*\s*$/;
return String(e).search (filter) != -1;
}

Sometimes most of the registration and login page need to validate email. In this example you will learn simple email validation.
First take a text input in html and a button input like this
<input type='text' id='txtEmail'/>
<input type='submit' name='submit' onclick='checkEmail();'/>
<script>
function checkEmail() {
var email = document.getElementById('txtEmail');
var filter = /^(([^<>()\[\]\\.,;:\s#"]+(\.[^<>()\[\]\\.,;:\s#"]+)*)|(".+"))#((\[[0-9]{1,3}\.[0-9]{1,3}\.[0-9]{1,3}\.[0-9]{1,3}])|(([a-zA-Z\-0-9]+\.)+[a-zA-Z]{2,}))$/;
if (!filter.test(email.value)) {
alert('Please provide a valid email address');
email.focus;
return false;
}
}
</script>
you can also check using this regular expression
<input type='text' id='txtEmail'/>
<input type='submit' name='submit' onclick='checkEmail();'/>
<script>
function checkEmail() {
var email = document.getElementById('txtEmail');
var filter = /^([a-zA-Z0-9_\.\-])+\#(([a-zA-Z0-9\-])+\.)+([a-zA-Z0-9]{2,4})+$/;
if (!filter.test(email.value)) {
alert('Please provide a valid email address');
email.focus;
return false;
}
}
</script>
Check this demo output which you can check here
function checkEmail() {
var email = document.getElementById('txtEmail');
var filter = /^(([^<>()\[\]\\.,;:\s#"]+(\.[^<>()\[\]\\.,;:\s#"]+)*)|(".+"))#((\[[0-9]{1,3}\.[0-9]{1,3}\.[0-9]{1,3}\.[0-9]{1,3}])|(([a-zA-Z\-0-9]+\.)+[a-zA-Z]{2,}))$/;
if (!filter.test(email.value)) {
alert('Please provide a valid email address');
email.focus;
return false;
}
}
<input type='text' id='txtEmail'/>
<input type='submit' name='submit' onclick='checkEmail();'/>
if email invalid then give alert message , if valid email then no alert message .
for more info about regular expression
https://www.w3schools.com/jsref/jsref_obj_regexp.asp
hope it will help you

You may be interested in this question (or this one), which highlights the fact that identifying valid email addresses via regexps is a very hard problem to solve (if at all solvable)

with more simple regex
Here it is :
var regexEmail = /\w+([-+.']\w+)*#\w+([-.]\w+)*\.\w+([-.]\w+)*/;
var email = document.getElementById("txtEmail");
if (regexEmail.test(email.value)) {
alert("It's Okay")
} else {
alert("Not Okay")
}
good luck.

function isEmailAddress(str) {
var pattern =/^\w+([\.-]?\w+)*#\w+([\.-]?\w+)*(\.\w{2,3})+$/;
return pattern.test(str); // returns a boolean
}

Email validation is easy to get wrong. I would therefore recommend that you use Verimail.js.
Why?
Syntax validation (according to RFC 822).
IANA TLD validation
Spelling suggestion for the most common TLDs and email domains
Deny temporary email account domains such as mailinator.com
jQuery plugin support
Another great thing with Verimail.js is that it has spelling suggestion for the most common email domains and registered TLDs. This can lower your bounce rate drastically for users that misspell common domain names such as gmail.com, hotmail.com, aol.com, aso..
Example:
test#gnail.com -> Did you mean test#gmail.com?
test#hottmail.con -> Did you mean test#hotmail.com?
How to use it?
The easiest way is to download and include verimail.jquery.js on your page.
After that, hookup Verimail by running the following function on the input-box that needs the validation:
$("input#email-address").verimail({
messageElement: "p#status-message"
});
The message element is an optional element that displays a message such as "Invalid email.." or "Did you mean test#gmail.com?". If you have a form and only want to proceed if the email is verified, you can use the function getVerimailStatus as shown below:
if($("input#email-address").getVerimailStatus() < 0){
// Invalid email
}else{
// Valid email
}
The getVerimailStatus-function returns an integer code according to the object Comfirm.AlphaMail.Verimail.Status. As shown above, if the status is a negative integer value, then the validation should be treated as a failure. But if the value is greater or equal to 0, then the validation should be treated as a success.

You can also try this expression, I have tested it against many email addresses.
var pattern = /^[A-Za-z0-9._%+-]+#([A-Za-z0-9-]+\.)+([A-Za-z0-9]{2,4}|museum)$/;

It would be best to use:
var pattern = /^\w+#[a-zA-Z_]+?\.[a-zA-Z]{2,20}$/;
This allows domains such as: whatever.info (4 letters at the end)
Also to test, using
pattern.test("exampleemail#testing.info")
returns true if it works
http://www.w3schools.com/js/js_obj_regexp.asp

I have been using this one....
/^[\w._-]+[+]?[\w._-]+#[\w.-]+\.[a-zA-Z]{2,6}$/
It allows that + before # (xyz+abc#xyz.com)

Little late to the party, but here goes nothing...
function isEmailValid(emailAdress) {
var EMAIL_REGEXP = new RegExp('^[a-z0-9]+(\.[_a-z0-9]+)*#[a-z0-9-]+(\.[a-z0-9-]+)*(\.[a-z]{2,15})$', 'i');
return EMAIL_REGEXP.test(emailAdress)
}
http://jsfiddle.net/yrshaikh/xvd6H/

var emailRegex = /^[A-Z0-9_'%=+!`#~$*?^{}&|-]+([\.][A-Z0-9_'%=+!`#~$*?^{}&|-]+)*#[A-Z0-9-]+(\.[A-Z0-9-]+)+$/i;
if(emailRegex.test('yoursamplemail'))
alert('valid');
else
alert('invalid');

Simple but powerful email validation for check email syntax :
var EmailId = document.getElementById('Email').value;
var emailfilter = /^[\w._-]+[+]?[\w._-]+#[\w.-]+\.[a-zA-Z]{2,6}$/;
if((EmailId != "") && (!(emailfilter.test(EmailId ) ) )) {
msg+= "Enter the valid email address!<br />";
}

You should bear in mind that a-z, A-Z, 0-9, ., _ and - are not the only valid characters in the start of an email address.
Gmail, for example, lets you put a "+" sign in the address to "fake" a different email (e.g. someone#gmail.com will also get email sent to someone+else#gmail.com).
micky.o'finnagan#wherever.com would not appreciate your code stopping them entering their address ... apostrophes are perfectly valid in email addresses.
The Closure "check" of a valid email address mentioned above is, as it states itself, quite naïve:
http://code.google.com/p/closure-library/source/browse/trunk/closure/goog/format/emailaddress.js#198
I recommend being very open in your client side code, and then much more heavyweight like sending an email with a link to really check that it's "valid" (as in - syntactically valid for their provider, and also not misspelled).
Something like this:
var pattern = /[^#]+#[-a-z\.]\.[a-z\.]{2,6}/
Bearing in mind that theoretically you can have two # signs in an email address, and I haven't even included characters beyond latin1 in the domain names!
http://www.eurid.eu/en/eu-domain-names/idns-eu
http://haacked.com/archive/2007/08/21/i-knew-how-to-validate-an-email-address-until-i.aspx

You can add a function to String Object
//Add this wherever you like in your javascript code
String.prototype.isEmail = function() {
return !!this.match(/^\w+#[a-zA-Z_]+?\.[a-zA-Z]{2,3}$/);
}
var user_email = "test.email#example.com";
if(user_email.isEmail()) {
//Email is valid !
} else {
//Email is invalid !
}