Regular expression not to allow whitespace at the end of email

Question

I am trying to accept an email without having whitespace or blank at the end. I have tried two variants

pattern="^[A-Za-z0-9._%+-]+@[a-z0-9.-]+.[a-z]{1,4}[^\s]+$">

pattern="^[A-Za-z0-9._%+-]+@[a-z0-9.-]+.[a-z]{1,4}\S$">

both are not working & input is accepting whitespace at the end. My full input line is

input type="email" id="guestUserEmail" name="guestEmail" data-pattern-error="Email is invalid" data-required-error="Please enter email address" required pattern="^[A-Za-z0-9._%+-]+@[a-z0-9.-]+.[a-z]{1,4}$"

I referred this answer regex for no whitespace at the begining and at the end but allow in the middle

Please suggest!

Answer 1

Update

HTML by default collapses whitespace. This means:

• If there are more than one whitespace between chars, it will render as a single whitespace char.

  • ex.this string has a double space right here .
    will render as:
    this string has a double space right here .

• Leading and trailing whitespace are stripped (this doesn't happen with strings hence the necessity for methods such as trim())

  • ex. abc123@email.com   
    will render as:
    abc123@email.com

So if you have a billion spaces after the email address, it will be automatically stripped in an <input>. The Demo has your <input> wrapped in a <form> and the form will actually send data to a real test server. If you send a valid email address with trailing whitespace, look at the response. You'll see that in the response, that the value has no trailing whitespace.

---

Have you considered escaping the periods?

A . means ANY one char

A \. means a dot or period

It looks like this works:

[A-Za-z0-9._%+-]+@[a-z0-9.-]+\.[a-z]{1,4}\S$

See tests at RegEx101

---

Demo

input {
  font: inherit
}

<form id='contact' action='https://httpbin.org/post' method='post'>
  <input type="email" id="guestEmail" name="guestEmail" pattern="^[A-Za-z0-9._%+-]+@[a-z0-9.-]+\.[a-z]{1,4}$" required placeholder='abc123@email.com'>
  <input type='submit'>
</form>

Answer 2

Java escape sequence will not consider \, you have to append one more slash, like this \\.

Modify your String pattern, like this

^[A-Za-z0-9._%+-]+@[a-z0-9.-]+.[a-z]{1,4}[^\\S]+$

This will resolve,

Answer 3

I think your regexes are ok:

https://regex101.com/r/j0MXV5/1

https://regex101.com/r/oN9v8U/1

Maybe it is an option to use blur and trim the either the leading and trailing whitespaces:

onblur="this.value=this.value.trim();

Or only the trailing whitespaces:

onblur="this.value=this.value.replace(/\s+$/, '');

<form>
    <input type="email" id="guestUserEmail" name="guestEmail" data-pattern-error="Email is invalid" data-required-error="Please enter email address" required pattern="^[A-Za-z0-9._%+-]+@[a-z0-9.-]+.[a-z]{1,4}[^\\S]+$" onblur="this.value=this.value.replace(/\s+$/, '');">
</form>

Answer 4

You are using a HTML input field of type email. The defined and documented behavior of this element is to accept but remove any leading or trailing whitespace. If that's not acceptable, don't use this element.

Your attempt at "fixing" the regex are misdirected. Basic regex reading skills should tell you that the apparent original regex only allows alphabetics just before end of string. Your attempts would basically change it from "mostly nearly correct email" to "mostly nearly correct email, followed by any junk at all, as long as it's not whitespace".

Generally speaking, you fix a too-permissive regex by constraining it more (dropping some stuff it would previously accept, perhaps refactoring the regex along the way; for example, to only allow internal dashes in a domain part, you have to split it into first character, optional middle perhaps with dashes, slightly less optional last character without a dash) but certainly not by adding new matching possibilities -- especially not a broad generic character class repeated an arbitrary number of times.

As already noted in comments, there is no way to completely match every valid email address with a regex, but the regular built-in validation in HTML5 is pretty much guaranteed to do a better job than a random regex you found on some PHP forum.

Answer 5

Use this RegEx. It will validate your email with or without white space at start or end of email id

^([^\S/.]{0,})+(([^<>()[\]\.,;:\s@\"]+(\.[^<>()[\]\.,;:\s@\"]+)*)|(\".+\"))@(([^<>()[\]\.,;:\s@\"]+\.)+[^<>()[\]\.,;:\s@\"]{2,})+([^\S/.]{0,})$