How to validate an email address in JavaScript
                                // Html form call function name at submit button
    <form name="form1" action="#"> 
    <input type='text' name='text1'/>
    <input type="submit" name="submit" value="Submit" 
    onclick="ValidateEmail(document.form1.text1)"/>
   </from>
    // Write the function name ValidateEmail below
    <script>
     function ValidateEmail(inputText)
    {
  var mailformat = /^[a-zA-Z0-9.!#$%&'*+/=?^_`{|}~-]+@[a-zA-Z0-9-]+(?:\.[a-zA-Z0-9-]+)*$/;
    if(inputText.value.match(mailformat))
    {
    alert("Valid email address!");
    document.form1.text1.focus();
    return true;
    }
    else
   {
    alert("You have entered an invalid email address!");
    document.form1.text1.focus();
    return false;
    }
    }
   </script>