Email validator

Question

Having troubles with my email validation code. I keep on getting the error that my function is not defined. i have made a javascript file for the java code and then i used the onchange in my html to trigger the function.

 <input type="text" id="email" name="email" onchange="check();" /> function check() { email = document.getElementById("email").value; filter = /^([a-zA-Z0-9_\.\-])+\@(([a-zA-Z0-9\-])+\.)+([a-zA-Z0-9]{2,4})+$/; if (filter.test(email.value)) { document.getElementById("email").style.border = "3px solid green"; return true; } else { document.getElementById("email").style.border = "3px solid red"; return false; } }

Since when was + an invalid character in email addresses? And why can't a TLD have more than 4 characters in it? — Quentin
– Quentin, Commented Dec 23, 2011 at 0:18
+1 from me. No need to down vote. OP is asking for why getting javascript error which is not even caused by the regex. — Ray Cheng
– Ray Cheng, Commented Dec 23, 2011 at 0:21
Sorry im still not used to the way that i have to post a question — MunLau
– MunLau, Commented Dec 23, 2011 at 0:27

Ray Cheng · Accepted Answer · 2011-12-23 00:19:29Z

Put your javascript in <script> tags.

Also rename your variable name email since your textbox is using it already.

<input type="text" id="email" name="email" onchange="check();" /> <script type="text/javascript"> function check() { var email_x = document.getElementById("email").value; filter = /^([a-zA-Z0-9_\.\-])+\@(([a-zA-Z0-9\-])+\.)+([a-zA-Z0-9]{2,4})+$/; if (filter.test(email.value)) { document.getElementById("email").style.border = "3px solid green"; return true; } else { document.getElementById("email").style.border = "3px solid red"; return false; } } </script>

Community · Accepted Answer · 2017-05-23 12:08:11Z

Email validation is not always as simple as your regular expression. Have you looked at:

Validate email address in JavaScript?

A better option would be to use Verimail.js. It's a simple script that takes care of it for you. With Verimail.js you could just do:

var email = "[email protected]"; var verimail = new Comfirm.AlphaMail.Verimail(); verimail.verify(email, function(status, message, suggestion){ if(status < 0){ // Incorrect syntax! }else{ // Syntax looks great! } });

The above example will hit the line 'Incorrect syntax!' because of the invalid TLD 'cmo'. Besides this, it will also give a suggestion that you can return to your user, in this case, the suggestion variable will contain '[email protected]' since 'fabeook.cmo' looks a lot like 'facebook.com'.

Hope this helps!

Tapan kumar · Accepted Answer · 2013-10-08 12:05:44Z

Here is the code for html input field and button field

 <input input type="text" name="txtEmailId" id="txtEmailId" /> <input type="submit" class="button" value="Suscribe" name="Suscribe" onclick="javascript:ShowAlert()" />

Now add the below function to the header of your page

 <script type="text/javascript"> function ShowAlert() { var email = document.getElementById('txtEmailId'); 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; } else { alert("Thanks for your intrest in us, Now you will be able to receive monthly updates from us."); document.getElementById('txtEmailId').value = ""; } } </script>

Here you can find the article on this Email Validation in JavaScript

Mr.BK · Accepted Answer · 2014-12-18 11:56:40Z

If you are specific about the domains , you may use this code for email validation so as to prevent anonymous email domains.

(^([a-zA-Z]{1,20}[-_.]{0,1}[a-zA-Z0-9]{1,20})(\@gmail\.com|\@yahoo\.com|\@hotmail\.com)$)

You may add additional domains too.

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