js对cookie的几个操作函数，网上找的（仅作备忘）
function getCookieVal(offset) {
var endstr = document.cookie.indexOf(";", offset);
if (endstr == - 1) {
endstr = document.cookie.length;
}
return unescape(document.cookie.substring(offset, endstr));
}
function getCookie(name) {
var arg = name + "=";
var alen = arg.length;
var clen = document.cookie.length;
var i = 0;
var j = 0;
while (i < clen) {
j = i + alen;
if (document.cookie.substring(i, j) == arg) return getCookieVal(j);
i = document.cookie.indexOf(" ", i) + 1;
if (i == 0) break;
}
return null;
}
function deleteCookie(name) {
var exp = new Date();
var cval = getCookie(name);
exp.setTime(exp.getTime() - 1);
document.cookie = name + "=" + cval + "; expires=" + exp.toGMTString();
}
var gCookieExpDays = 80;
function setCookie(name, value) {
var argv = setCookie.arguments;
var argc = setCookie.arguments.length;
var exp = (argc > 2) ? argv[2] : gCookieExpDays;
var path = (argc > 3) ? argv[3] : null;
var domain = (argc > 4) ? argv[4] : null;
var secure = (argc > 5) ? argv[5] : false;
var expires = new Date();
deleteCookie(name);
expires.setTime(expires.getTime() + (exp * 24 * 60 * 60 * 1000));
document.cookie = name + "=" + value + "; expires=" + expires.toGMTString() + ((domain == null) ? "": ("; domain=" + domain)) + ((path == null) ? "": ("; path=" + path)) + ((secure == true) ? "; secure": "");
}