Comments on: Check Email Address with JavaScript and Regular Expressions

By: Adnan

Adnan — Tue, 23 Jun 2009 13:33:01 +0000

Can you please explain the regular expression of this code and how its working? Also about .test – Is .test a default statement in javascript to check things like you did in the code above?

By: Gheesh

Gheesh — Sun, 24 May 2009 16:47:09 +0000

Just a small correction: The regular expression has an extra ()+ at the end. It should read:

^([a-zA-Z0-9_\.\-])+\@(([a-zA-Z0-9\-])+\.)+[a-zA-Z0-9]{2,4}$

With the first one any length TLDs would be accepted (which is not intrinsecally wrong as others have pointed out, but if that was the intention the expression could be shortened).

By: Robby Slaughter

Robby Slaughter — Mon, 16 Mar 2009 19:34:47 +0000

It also doesn’t appear to handle the plus character, which is valid.

See: http://www.dominicsayers.com/isemail/

On a larger note, this is a key problem with cutting-and-pasting code, one which deserves a full discussion in itself.

@robbyslaughter.com

By: Pande

Pande — Sun, 15 Mar 2009 00:30:31 +0000

Would be fine if we could find a solution to avoid fake e-mail addresses on comments on Wordpress

By: sanjay

sanjay — Tue, 02 Dec 2008 15:42:45 +0000

Just an FYI; I haven’t tried Ade’s solution but the pattern above doesn’t validate e-mail addresses with apostrophes in them.. (eg, Mike.O’Hare@Whatever.com). Apostrophes are valid per the RFC 2821/2822 –> http://www.faqs.org/rfcs/rfc2822.html

HTH,
Sanjay

By: Szubu - LorenB

Szubu - LorenB — Sun, 05 Oct 2008 06:16:40 +0000

btw, I really like what you have going on here, your tutorials are very simple, I will definately be bookmarking this one….

By: Szubu

Szubu — Sun, 05 Oct 2008 06:10:12 +0000

Hi there,

I am tring to use this in an existing form in real-time, but this doesnt appear to be validating in realtime like your password strength checker…

Or, am i just that clueless, and it aint workin for me?

By: gemp

gemp — Thu, 07 Aug 2008 14:25:02 +0000

There’s much simpler way to write the expression:
var regex = /^[a-z0-9\._-]+@([a-z0-9_-]+\.)+[a-z]{2,6}$/i;
- With the final modifier /i there’s no need to indicate the upper case range.
- I don’t know of any TLD with numbers in it.
On a side note, I do allow TLD with up to 6 chars; new ones arrive regularly and you never know (well, somme future ones may even have numbers in it, I know).

By: Android

Android — Thu, 24 Jul 2008 10:32:50 +0000

Perfect, just what I needed!

By: Douglas Karr

Douglas Karr — Fri, 02 Nov 2007 15:23:04 +0000

Hi Reg,

You can test out the Regex utilizing an Online Regex Tester.

Also, there’s definitely much more that can be done if you want to ensure an email address is valid in accordance with the RFC.

There are a few reasons not to allow someone to enter an invalid email address:
1. They will get annoyed at you when the email they expected doesn’t get through – regardless of whether or not it was your fault the address was entered incorrectly.
2. If com.museum was a valid domain and, let’s say, Yahoo! operated it – any email address that bounced would have a negative impact on your company’s reputation for email delivery. This could lead to all of your company’s email being blocked.
3. If your email service provider allowed you to enter bob@com.museum, you’d also pay for each email sent to that email address until they unsubscribed that address due to bounces. I would steer clear of any ESP that would allow an invalid email address like that – they’re just taking your money!

Thanks for stopping by!
Doug