var email = /^[a-zA-Z]{1}([a-zA-Z0-9]?[\.\-\_]{0,1}[a-zA-Z0-9]+)*[@]{1}(([a-zA-Z0-9]+[\.]{1})+([a-zA-Z]+))$/;

var password = /^[a-zA-Z0-9_]+$/;

var username = /^[a-zA-Z0-9_ ]+$/;

var numeric = /^[0-9]+$/;

var city = /^[a-zA-Z]+$/;

function validuser()
{
     if(document.getElementById('name').value == '');
     else
     {
         if(!document.getElementById('name').value.match(username))
         {     /* var name ='name';*/
              alert('Invalid user name:  Only alphabet and underscore are allowed.');
              document.getElementById('name').value="";
              /*document.form[0].name.focus();*/
         }
     }
}

function validemail()
{
    if(document.getElementById('email').value == '');
    else
    {
        //validation for email
        if(!document.getElementById('email').value.match(email))
        {
            alert('Please enter valid email adress.');
            document.getElementById('email').value='';
        }
    }
}
function validblank()
{
      if(document.getElementById('name').value == '' || document.getElementById('email').value == '')
           alert("Please fill all the field");
}