Email validation for textbox

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I wrote the following code to validate the textbox for email. It's not allowing DOT(.) but I want to allow the DOT(.) only once. Which one should I delete in the following code?

JavaScript

if(document.getElementById(txtemail).value=="")
      {
                 alert(Email id can not be blank)
                document.getElementById(txtemail).focus();
                return false;
      }
     var emailPat = /^(\.*\"|[A-Za-z]\w*)@(\[\d{1,3}(\.\d{1,3}){3}]|[A-Za-z]\w*(\.[A-Za-z]\w*)+)$/;
     var emailid=document.getElementById(txtemail).value;
     var matchArray = emailid.match(emailPat);
     if (matchArray == null)
    {
               alert("Your email address seems incorrect. Please try again.);
               document.getElementById(txtEmail).focus();
               return false;
    }

 }

Posted 22-Aug-10 20:08pm

venubabu k

Updated 24-Aug-10 7:57am

Deeksha Shenoy

v3

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Sandesh M Patil · Accepted Answer · 2010-08-24T07:06:00

Your validation expression is wrong.
Use below one

var emailPat = /^(\".*\"|[A-Za-z]\w*)@(\[\d{1,3}(\.\d{1,3}){3}]|[A-Za-z]\w*(\.[A-Za-z]\w*)+)$/

Or

See below JavaScript code to validate email id. We mostly use it

<script language="Javascript">


function echeck(str) {

		var at="@"
		var dot="."
		var lat=str.indexOf(at)
		var lstr=str.length
		var ldot=str.indexOf(dot)
		if (str.indexOf(at)==-1){
		   alert("Invalid E-mail ID")
		   return false
		}

		if (str.indexOf(at)==-1 || str.indexOf(at)==0 || str.indexOf(at)==lstr){
		   alert("Invalid E-mail ID")
		   return false
		}

		if (str.indexOf(dot)==-1 || str.indexOf(dot)==0 || str.indexOf(dot)==lstr){
		    alert("Invalid E-mail ID")
		    return false
		}

		 if (str.indexOf(at,(lat+1))!=-1){
		    alert("Invalid E-mail ID")
		    return false
		 }

		 if (str.substring(lat-1,lat)==dot || str.substring(lat+1,lat+2)==dot){
		    alert("Invalid E-mail ID")
		    return false
		 }

		 if (str.indexOf(dot,(lat+2))==-1){
		    alert("Invalid E-mail ID")
		    return false
		 }
		
		 if (str.indexOf(" ")!=-1){
		    alert("Invalid E-mail ID")
		    return false
		 }

 		 return true					
	}

function ValidateForm(){
	var emailID=document.frmSample.txtEmail
	
	if ((emailID.value==null)||(emailID.value=="")){
		alert("Please Enter your Email ID")
		emailID.focus()
		return false
	}
	if (echeck(emailID.value)==false){
		emailID.value=""
		emailID.focus()
		return false
	}
	return true
 }
</script>

Hope this may help you :)

singlaNitish · Accepted Answer · 2010-08-24T05:37:00

Solution 1

You can alternatively make use of regular expression validator
and then click on the expression property and select the internet email address... also select the control to validate and give the textbox which accepts email id.......

Hope this solves your problem. :) :thumbsup:

Posted 24-Aug-10 5:37am

singlaNitish

Updated 24-Aug-10 7:57am

v3

Comments

Sandesh M Patil 25-Aug-10 6:22am

wat if he want to use javascript insted of using regular expression validator?

singlaNitish 25-Aug-10 8:37am

sir i am new to .net so i wanted to know does there any security issues or so that i should opt for javascript code.

senguptaamlan 25-Aug-10 9:19am

if you require the validation at client side (ie at browser) then you have to use javascript. RegularExpression validator actually validates the string at client side(by emitting javascript) if you set True to EnableClientScript property. So writing javascript only make the development process a bit long (cause you need to write the logic, check for syntax check)rather than dragging nd dropping a RequiredFieldValidator and RegularExpressionValidator on the page.

singlaNitish 25-Aug-10 10:48am

so what i think is if both check on client side which is better also in speed aspect so why not to use regular field validator when it is provided in visual studio ....sorry if u feel i am arguing or so....

Sandesh M Patil 26-Aug-10 5:37am

See buudy, Requirefield validator is useful when we want to validate at both side i.e. Client and server side. However it makes load on the page means page require time to load but javascript get compiled when page first time load and so javascript makes validation faster and page performance increases

singlaNitish 26-Aug-10 5:46am

thanx a lot sir...

Sandesh M Patil 26-Aug-10 9:25am

Oh you are welcome. Please visit hindi forum below is the link

http://www.codeproject.com/Forums/1580229/Hindi.aspx

virang_21 · Accepted Answer · 2010-08-25T15:51:00

User Regular Expression Validation. That will be more elegant code.

<asp:textbox id="txtEmail" runat="server" maxlength="80" width="255px" xmlns:asp="#unknown"></asp:textbox>

               <asp:regularexpressionvalidator id="RegularExpressionValidator1" runat="server" xmlns:asp="#unknown">
                   ControlToValidate="txtEmail" ErrorMessage="Invalid Email"
   ValidationExpression="\w+([-+.']\w+)*@\w+([-.]\w+)*\.\w+([-.]\w+)*"></asp:regularexpressionvalidator>

Hiren solanki · Accepted Answer · 2010-08-27T00:32:00

Solution 4

Dont Do this type of complex operation.

Just Do.
1. attach regularexpression validator to your text box. which have a inbuilt email validation regex.

Thanks,
Dont forget to mark as a answer

Hiren Solanki

Posted 27-Aug-10 0:32am

Hiren solanki