how to check email validation in js code example

Example 1: js email regex

function isValidEmail(email) {
  const re = /^(([^<>()\[\]\\.,;:\s@"]+(\.[^<>()\[\]\\.,;:\s@"]+)*)|(".+"))@((\[[0-9]{1,3}\.[0-9]{1,3}\.[0-9]{1,3}\.[0-9]{1,3}\])|(([a-zA-Z\-0-9]+\.)+[a-zA-Z]{2,}))$/;
  return re.test(String(email).toLowerCase());
}

Example 2: Email validation using javascript

function checkEmail() {

    var email = document.getElementById('txtEmail');
    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;
 }
}

- Call the function on Email textbox

Example 3: validate email function

# Language: Perl

sub Validate_Email($)
{
   my $sEmail = $_[0];
   my $sRetMsg = "";

   my $sUserNmRegex = "^[[:alnum:]]+([.!#\$\%&'*+-\/=?^_'{|]?[[:alnum:]]+)*";
   my $sDomainRegex = "@[[:alnum:]]+([.-]{1}[[:alnum:]]+)*";
   my $sEndRegex = "([.]{1}[[:alnum:]]+)+";

   #  Work
   #--------#

   if ($sEmail =~ /$sUserNmRegex$sDomainRegex$sEndRegex$/) {
      $sRetMsg = "Email is valid";
   }
   else {
      $sRetMsg = "Email is not valid";
   }

   return $sRetMsg;
}

my $sEmail = '[email protected]';
print "[Email:$sEmail] : " . Validate_Email($sEmail) . "\n";

# OUTPUT -> [Email:[email protected]] : Email is valid