var valid_fields = new Array();

function alphanumeric_fvalidate(field, length)
{
	var reg = new RegExp("[^a-z0-9]", "i");
	if(reg.test(field.value))
	{
		alert('fail');
	}
	field.value = length_fvalidate(field, length);
}

function length_fvalidate(field, length)
{
	if(length > 0)
	{
		if(field.value.length > length)
		{
			return field.value.substr(0, length);
		}
	}
	return field.value;
}

function change_field_highlights()
{
	var fields = document.getElementsByTagName('input');
	for(var i = 0; i < fields.length; i++)
	{
		field = fields[i];
		if(field.className != '')
		{
			addEvent(field, 'focus', change_highlight);
			addEvent(field, 'blur', change_highlight);
		}
	}
	var fields = document.getElementsByTagName('textarea');
	for(var i = 0; i < fields.length; i++)
	{
		field = fields[i];
		if(field.className != '')
		{
			addEvent(field, 'focus', change_highlight);
			addEvent(field, 'blur', change_highlight);
		}
	}
}

function change_highlight()
{
	if(this.className.indexOf('_focus') != -1 )
	{
		this.className = this.className.substr(0, this.className.indexOf('_focus'));
	}
	else
	{
		this.className = this.className + '_focus';
	}
}