function a(){

	console.log(arguments.length);

	var c = [].slice.call(arguments);//类数组转成数组

	c.push(5);

	console.log(c);

	console.log(arguments);

}

a(1,2,3)

var a = [1,2,3],

 	b = a.slice(0);

 	a.push(5);

	console.log(a);

 	console.log(b);