javascript中document.cookie与Set-Cookie的区别?

document.cookie--A cookie is a small piece of information stored by the web browser in the cookies.txt file. Use string methods such as substring, charAt, indexOf, and lastIndexOf to determine the value stored in the cookie. See the JavaScript Guide for a complete specification of the cookie.

Set-Cookie--function setCookie (sName, vValue)
{
var argv = setCookie.arguments, argc = setCookie.arguments.length;
var sExpDate = (argc > 2) ? "; expires="+argv[2].toGMTString() : "";
var sPath = (argc > 3) ? "; path="+argv[3] : "";
var sDomain = (argc > 4) ? "; domain="+argv[4] : "";
var sSecure = (argc > 5) && argv[5] ? "; secure" : "";
document.cookie = sName + "=" + escape(vValue,0) + sExpDate + sPath + sDomain + sSecure + ";";
}

上面的例子你看懂了么？？？？一个是系统的方法，另一个是用户自定义的方法。。。。