javascript cookie 操作 读取和写入

function readCookie(nm){
var m="";
if(window.RegExp){
var re=new RegExp(";\\s*"+nm+"=([^;]*)","i");
m=re.exec(';'+document.cookie);
}
return(m?unescape(m[1]):"");
}
//存
function createCookie(nm,val,y){
var exp="";
if(y){
var dt=new Date();
dt.setTime(dt.getTime()+(y*86400000));
exp="; expires="+dt.toGMTString();
}
document.cookie=nm+"="+escape(val)+exp+";path=/";
}