JS如何操作cookie

function getCookie(c_name) {    if (document.cookie.length>0) {        c_start=document.cookie.indexOf(c_name + "=")        if (c_start!=-1)         {            c_start=c_start + c_name.length+1            c_end=document.cookie.indexOf(";",c_start)            if (c_end==-1) {                c_end=document.cookie.length            }        return   unescape(document.cookie.substring(c_start,c_end))；    }  }  }function setCookie(c_name,value,expiredays) {    var date = new Date();    date.setDate(date.getDate()+expiredays*24*60*60*1000);    var expires = 'expires=' + data.toGMTString();    document.cookie = c_name+ "=" + value + ';' + expires;}