script中函数的变参数

<html>
<head>
<meta http-equiv="Content-Type" content="text/html; charset=utf-8" />
<script type="text/javascript">
	function add() {
	    var length = arguments.length;
		var c = 0;
		for (var i = 0; i < length; i++) {
		    c += arguments[i];
		}
		return c;
	}
	
	document.write("<p>无参数 = " + add() + "</p>");
	document.write("<p>有参数 = " + add(1,2,3) + "</p>");
</script>
</head>
<body>
</body>
</html>