How to use email validation in Java script.Like User can't enter invalid email address?

Questions by mrbaliram   answers by mrbaliram

  

Editorial / Best Answer

bicu  

  • Member Since Sep-2005 | Feb 2nd, 2006

First of all, here is the javascript function that tests if an email address is valid.
It checks for a lot of things: to see if the email contains a "@" sign and a dot, checks to see if the @ is before the dot, and so on.

<script>
function isMail(str)
{
   var at="@";
   var dot=".";
   var lat=str.indexOf(at);
   var lstr=str.length;
   var ldot=str.indexOf(dot);
   if (str.indexOf(at)==-1) return false;
   if (str.indexOf(at)==-1 || str.indexOf(at)==0 || str.indexOf(at)==lstr) return false;
   if (str.indexOf(dot)==-1 || str.indexOf(dot)==0 || str.indexOf(dot)==lstr) return false;
   if (str.indexOf(at,(lat+1))!=-1) return false; if (str.substring(lat-1,lat)==dot || str.substring(lat+1,lat+2)==dot) return false;
   if (str.indexOf(dot,(lat+2))==-1) return false;
   if (str.indexOf(" ")!=-1) return false;
   return true;
}

// the next function will be used to validate the form. I made this as a separate function because you might want to validate more fields.
function validate_form()
{
   if (!isMail(document.form1.mail.value))
   {
      alert("Please enter a valid email address");
      document.form1.mail.focus();
      return false;
   }
   // if the value entered is not a valid email address, 
   // we show a message, focus on the field and return false.
   // returning false will make sure the form is not submitted

   // if we got here, it means the email address is valid
   return true;
   // return true means that the form is submitted.
}
</script>

After placing this function in the code, here is what you need to put in the form.

Let's say the form only has the email address and a submit button.

<form action="/" method="post" onsubmit="return validate_form()" name="form1">
<input type="text" name="email" value="">
<input type="submit" name="submit_button" value="continue">
</form>

Showing Answers 1 - 13 of 13 Answers

bicu

  • Feb 2nd, 2006
 

First of all, here is the javascript function that tests if an email address is valid.
It checks for a lot of things: to see if the email contains a "@" sign and a dot, checks to see if the @ is before the dot, and so on.

<script>
function isMail(str)
{
   var at="@";
   var dot=".";
   var lat=str.indexOf(at);
   var lstr=str.length;
   var ldot=str.indexOf(dot);
   if (str.indexOf(at)==-1) return false;
   if (str.indexOf(at)==-1 || str.indexOf(at)==0 || str.indexOf(at)==lstr) return false;
   if (str.indexOf(dot)==-1 || str.indexOf(dot)==0 || str.indexOf(dot)==lstr) return false;
   if (str.indexOf(at,(lat+1))!=-1) return false; if (str.substring(lat-1,lat)==dot || str.substring(lat+1,lat+2)==dot) return false;
   if (str.indexOf(dot,(lat+2))==-1) return false;
   if (str.indexOf(" ")!=-1) return false;
   return true;
}

// the next function will be used to validate the form. I made this as a separate function because you might want to validate more fields.
function validate_form()
{
   if (!isMail(document.form1.mail.value))
   {
      alert("Please enter a valid email address");
      document.form1.mail.focus();
      return false;
   }
   // if the value entered is not a valid email address, 
   // we show a message, focus on the field and return false.
   // returning false will make sure the form is not submitted

   // if we got here, it means the email address is valid
   return true;
   // return true means that the form is submitted.
}
</script>

After placing this function in the code, here is what you need to put in the form.

Let's say the form only has the email address and a submit button.

<form action="/" method="post" onsubmit="return validate_form()" name="form1">
<input type="text" name="email" value="">
<input type="submit" name="submit_button" value="continue">
</form>

michael

  • Aug 6th, 2006
 

a better way is to use regular expression

toneerajkumar

  • Dec 6th, 2006
 

script for email validations// check if email field is blankif (theForm.Email.value == ""){alert("Please enter a value for the "Email" field.");theForm.Email.focus();return (false);}// test if valid email address, must have @ and .var checkEmail = "@.";var checkStr = theForm.Email.value;var EmailValid = false;var EmailAt = false;var EmailPeriod = false;for (i = 0; i < checkStr.length; i++){ch = checkStr.charAt(i);for (j = 0; j < checkEmail.length; j++){if (ch == checkEmail.charAt(j) && ch == "@")EmailAt = true;if (ch == checkEmail.charAt(j) && ch == ".")EmailPeriod = true; if (EmailAt && EmailPeriod) break; if (j == checkEmail.length) break; } // if both the @ and . were in the stringif (EmailAt && EmailPeriod){ EmailValid = true break; }}if (!EmailValid){alert("The "email" field must contain an "@" and a ".".");theForm.Email.focus();return (false);}

Saurabh

  • May 3rd, 2007
 

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

Use this regular expression

You can be more strict by using .com,.biz,.org,.arpa etc in regular expression

SwapnilSwapnil

  • Sep 7th, 2009
 

There are many varieties of email validation. This one is simple, but effective.

function isValidEmail(str) {

   return (str.indexOf(".") > 2) && (str.indexOf("@") > 0);
 }

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Ravi Maggon

  • May 16th, 2011
 

<html>
  <head>
    <script type="text/javascript">
  function check()
   {
    var filter=/^[a-zA-Z0-9]+[a-zA-Z0-9_.-]+[a-zA-Z0-9_.]+@[a-zA-Z0-9]+[a-zA-Z0-9_-]+[a-zA-Z0-9]+.[a-z]{2,4}$/;
     if(!filter.test(document.getElementById("email").value))
     {
      alert("Wrong Email Id");
      return false;
     } else {
      alert("Correct Email Id");
      return true;
     }
   }
    </script>
  </head>
  <body>
    <form action="" onsubmit="return check()">
   <input type="text" name="email" id="email" />
   <input type="submit" value="submit" />
    </form>
  </body>
</html>

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