JS 判断数组中是否包含某个元素

<script type="text/javascript">
	Array.prototype.S = String.fromCharCode(2);
	Array.prototype.in_array = function(e) {
		var r = new RegExp(this.S + e + this.S);
		return (r.test(this.S + this.join(this.S) + this.S));
	};

	var arr = [ "xml", "html", "css", "js" ];
	var b = arr.in_array("css");
	//如果 存在返回true , 不存在返回false
	alert(b);
</script>