function isValidEmail(str) {
   return (str.indexOf(".") > 2) && (str.indexOf("@") > 0);
 }
function check_feedback_form()
{
	var username=document.getElementById('feedback_comment').value;	
	if(username=="")
	{
		alert('Your feedback field is empty !');
		document.getElementById('feedback_comment').focus();
		return false;
	}
}
function check_feedback_form2()
{
	var comment_name=document.getElementById('comment_name').value;
	var comment_email=document.getElementById('comment_email').value;	
	var feedback_comment=document.getElementById('feedback_comment').value;	
    var antispam=document.getElementById('antispam').value;	
	if(comment_name=="")
	{
		alert('Please Enter Your Name !');
		document.getElementById('comment_name').focus();
		return false;
	}
	if(comment_email=="")
	{
		alert('Please Enter Your Email !');
		document.getElementById('comment_email').focus();
		return false;
	}
	if(!isValidEmail(comment_email)){
		alert('Your Email Address Invalid !');
		document.getElementById('comment_email').focus();
		return false;
	}
	if(feedback_comment=="")
	{
		alert('Your feedback field is empty !');
		document.getElementById('feedback_comment').focus();
		return false;
	}
    if(antispam=="")
	{
		alert('Please enter Anti-Spam image code !');
		document.getElementById('antispam').focus();
		return false;
	}
}
function check_login_form()
{
	var username=document.getElementById('username').value;
	var password=document.getElementById('password').value;	
	if(username=="")
	{
		alert('Please Enter Your Username !');
		document.getElementById('username').focus();
		return false;
	}
	if(password=="")
	{
		alert('Please Enter Your Password !');
		document.getElementById('password').focus();
		return false;
	}
}
function check_register_form()
{
	var reg_username=document.getElementById('reg_username').value;
	var reg_password=document.getElementById('reg_password').value;	
	var reg_repassword=document.getElementById('reg_repassword').value;	
	if(reg_username=="")
	{
		alert('Please Enter Your Username !');
		document.getElementById('reg_username').focus();
		return false;
	}
	if(reg_username.length < 4)
	{
		alert('Username length most more 4 characters !');
		document.getElementById('reg_username').focus();
		return false;
	}
	if(reg_password=="")
	{
		alert('Please Enter Your Password !');
		document.getElementById('reg_password').focus();
		return false;
	}
	if(reg_repassword=="")
	{
		alert('Please Enter Your Retype Password !');
		document.getElementById('reg_repassword').focus();
		return false;
	}
	if(reg_password!=reg_repassword){
		alert('Password and Retype Password Not Match !');
		document.getElementById('reg_repassword').focus();
		return false;
	}
}