jquery.validator.js

(function($) {
	var rules = {
		body: function(val) {
			if (val.length == 0) return 'requires body';
			if (val.length <= 100) return 'body has a 100 character limit';
			return true;
		},

		nickname: function(val) {
			return val.length <= 20 ? true : 'nick has a 20 character limit';
		},

		password: function(val) {
			return (val.length >= 8 && val.length <= 16) ? true : 'passward has a 8-16 character limit';
		},

		email: function(val) {
			return /^(?:(?:(?:(?:[a-zA-Z0-9_!#\$\%&'*+/=?\^`{}~|\-]+)(?:\.(?:[a-zA-Z0-9_!#\$\%&'*+/=?\^`{}~|\-]+))*)|(?:"(?:\\[^\r\n]|[^\\"])*")))\@(?:(?:(?:(?:[a-zA-Z0-9_!#\$\%&'*+/=?\^`{}~|\-]+)(?:\.(?:[a-zA-Z0-9_!#\$\%&'*+/=?\^`{}~|\-]+))*)|(?:\[(?:\\\S|[\x21-\x5a\x5e-\x7e])*\])))$/.test(val) ?
				true :
				'invalid Email address';
		}
	};

	$.fn.validate = function(type) {
		var validator = rules[type];
		return validator ?
			this.blur(function() {
				var input = $(this);
				$('+ .error', input).remove();

				var r = validator(input.val());
				if (r === true)
					input.removeClass('error');
				else
					input.addClass('error').after('<p class="error">'+r+'</p>');
			}) :
			this;
	};
})(jQuery);