// new prototype defintion
function change_image(obj_id,img)
{
  	get_object(obj_id).src = img;
}
function changeColor(obj_id,req_color)
{
	get_object(obj_id).style.color=req_color;
}
function changeClass(obj_id,class_name)
{
	get_object(obj_id).className=class_name;
}
function get_object(obj_id)
{
	if(document.getElementById(obj_id))
	{
		return document.getElementById(obj_id);
	}
	else
	{
		alert("Object not exists with id: ".obj_id);
		return false;
	}
}
function get_objectvalue(obj_id)
{
	return get_object(obj_id).value;
}

////////validation functions////////////

function validate_float(obj_id)
{
	var floatExp =/^[0-9]*\.?[^\.][0-9]*$/;
	return validate_field_withexp(obj_id,floatExp);
}
function validate_email(obj_id)
{
	var emailExp = /^[\w\-\.\+]+\@[a-zA-Z0-9\.\-]+\.[a-zA-z0-9]{2,4}$/;
	return validate_field_withexp(obj_id,emailExp);
}
function validate_words(obj_id)
{
	var wordExp = /^[a-zA-Z_]+([a-zA-Z_ ]*)$/;
	return validate_field_withexp(obj_id,wordExp);
}
function validatte_website(obj_id)
{
   	var websiteurl =/https?:\/\/([-\w\.]+)+(:\d+)?(\/([\w\/_\.]*(\?\S+)?)?)?/;
	return validate_field_withexp(obj_id,websiteurl);
}
function validate_digits(obj_id)
{
	var digitExp = /\d/;
	return validate_field_withexp(obj_id,digitExp);
}
function validate_ten_digits(obj_id)
{
	var digitExp = /\d{10}/;
	return validate_field_withexp(obj_id,digitExp);
}
function validate_zip(obj_id)
{
	var zipExp = /^\d{5}(-\d{4})?$/;
	return validate_field_withexp(obj_id,zipExp);
}
function validate_exwords(obj_id)
{
	var exwordExp = /^[a-z A-Z 0-9 - _ ' ,]+([a-z A-Z 0-9 - _ ' ,]*)$/;
	return validate_field_withexp(obj_id,exwordExp);
}
function validate_notnull(obj_id)
{
	if(get_objectvalue(obj_id)!="")
	{
		return true;
	}
	else
	{
		return false;
	}
}
function validate_field_withexp(obj_id,reg_exp)
{
	return reg_exp.test(get_objectvalue(obj_id));
}
function validate_image_extension(obj_id,extension)
{
	if(get_objectvalue(obj_id)!="")
	{
		get_extension=get_objectvalue(obj_id).indexOf(extension);
		if((get_extension=="-1")||(get_extension != (get_objectvalue(obj_id).length)-3))
		{
			return false;
		}
	}
	else
	{
		return false;
	}
	return true;
}

function validate_form()
{
	if(!validate_email("email"))
	{
		alert("Please Provide E-mai Address!");
		$("email").focus();
		return false;
	}
	if(!validate_notnull("msg"))
	{
		alert("Please Provide Message!");
		$("msg").focus();
		return false;
	}
	return true;
}