Javascript Email Address Validation example

I have tried a bunch of JavaScript email validation routines available on the net but this one SmartWebby worked best for me. I have used it several times it just great. This javascript validation code is cross browser compatible (works for all browsers). The following example shows how you can validate an email address for a form.

Here is how the JavaScript Email Address Validation work for the given code:

Function echeck is used to verify if the given value is a possible valid email address. This function simply verifies the following:

1. It makes sure the email address has only one (@) and that it is not at the end or beginning of the email address.
2. It makes sure the email address has atleast one (.) after the @.
3. It also makes sure that there are no spaces, extra '@'s or a (.) just before or after the @.

Email Validation Example

Enter an Email Address :

JavaScript Code

<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>

HTML Code

<form name="frmSample" method="post" action="#" onSubmit="return ValidateForm()">
<p>Enter an Email Address : 
 <input type="text" name="txtEmail">
</p>
<p> 
<input type="submit" name="Submit" value="Submit">
</p>
</form>

Courtesy of SmartWebby.com