function  checkForm(this_form){
    if  (!hasValue(this_form.name, "TEXT" )) {
                if  (!putMessage("Please enter your name")){
                        return false; 
                }
        }
    if  (!hasValue(this_form.email, "TEXT" )) {
                if  (!putMessage("Please enter your email address")){
                        return false; 
                }
        } else {
                if (!checkEmail(this_form.email)){
                        if  (!putMessage("Please enter valid email address")){
                                return false; 
                        }
                }
        }
	if  (!hasValue(this_form.comments, "TEXT" )) {
                if  (!putMessage("Please enter your comments")){
                        return false; 
                }
        }
	
    
	
        
        return true;    
}



function putMessage(error_message){
        alert(error_message);
        return false;   
}

function checkEmail(email){
        var email_string = email.value; 
        var at_position = email_string.indexOf('@'); 
        var dot_position = email_string.indexOf('.', at_position); 
        var extension = email_string.substring(dot_position+1,email_string.length); 
        
        if(at_position<0){
                return false; 
        } else if (dot_position<0){
                return false; 
        } else if (extension.length<=0){
                return false; 
        } 
        return true; 
}

function hasValue(obj, obj_type){
    if (obj_type == "TEXT" || obj_type == "PASSWORD"){
        if (obj.value.length == 0) 
                return false;
        else 
                return true;
    } else if (obj_type == "SINGLE_VALUE_RADIO" || obj_type == "SINGLE_VALUE_CHECKBOX") {
                if (obj.checked)
                        return true;
                else
                return false;   
        } else if (obj_type == "RADIO" || obj_type == "CHECKBOX") {
                for (i=0; i < obj.length; i++){
                        if (obj[i].checked)
                                return true;
                }
                return false;   
        } else  if (obj_type == "SELECT") {
                if (obj.selectedIndex == 0)
                        return false;
                else
                        return true;
        }
}

function hasValue2(obj1, obj2, obj3, obj4, obj5, obj6){
        var flag = 0;
        for (i=1; i < 7; i++){
                if (obj[i].checked)
                        flag = i;
                }
        if (flag == 0)
                return false;
        else
                return true;
}