var eng = {
			'your_name' : 'your name',
			'your_email' : 'your email address',
			'friend_name' : 'friend\'s name',
			'friend_email' : 'friend\'s email address'
			};

function resetFields(whichform)
{
	for (var i = 0; i < whichform.elements.length; i++)
	{
		var element = whichform.elements[i];
		if (element.type == "submit") continue;
		if (!element.defaultValue) continue;
		element.onfocus = function()
		{
			if (this.value == this.defaultValue)
			{
				this.value = "";
			}
		}
		element.onblur = function()
		{
			if (this.value == "")
			{
				this.value = this.defaultValue;
			}
		}
	}
}

function validateForm(whichform)
{
	for (var i = 0; i < whichform.elements.length; i++)
	{
		var element = whichform.elements[i];
		if (element.className.indexOf("required") != -1)
		{
			if(!isFilled(element))
			{
				alert("Please fill in the " + eng[element.name] + " field.");
				return false;
			}
		}
		if (element.className.indexOf("email") != -1)
		{
			if (!isEmail(element))
			{
				alert("The " + eng[element.name] + " field must be a valid email address.");
				return false;
			}
		}
	}

	return true;
}

function isFilled(field)
{
	if (field.value.length < 1 || field.value == field.defaultValue)
		return false;
	else
		return true;
}

function isEmail(field) 
{
	if (field.value.indexOf("@") == -1 || field.value.indexOf(".") == -1)
		return false;
	else
		return true;
}

function prepareForms()
{
	for (var i=0; i<document.forms.length; i++)
	{
		var thisform = document.forms[i];
		resetFields(thisform);
		thisform.onsubmit = function()
		{
			return validateForm(this);
		}
	}
}

addLoadEvent (prepareForms);