js实现cookie跨域功能

/**
   * 设置cookie方法
   * @param   {string}  name  cookie键值
   * @return  {*}  返回cookie值
   */
  function setCookie_log(c_name,value,domain){
    var exdate = new Date(), expiredays = 365;
    exdate.setDate(exdate.getDate() + expiredays);
    //判断是否需要跨域存储
    if (domain) {
        document.cookie = c_name+ "=" +escape(value)+((expiredays==null) ? "" : ";expires="+exdate.toGMTString())+";path=/;domain=xueersi.com";
    } else {
        document.cookie = c_name+ "=" +escape(value)+((expiredays==null) ? "" : ";expires="+exdate.toGMTString())+";path=/";
    }    
  }
  /**
   * 获取cookie方法
   * @param   {string}  name  cookie键值
   * @return  {*}  返回cookie值
   */
  function getCookie_log(name){
    if (document.cookie.length>0){
      var start=document.cookie.indexOf(name + "=");
      if(start != -1){ 
        start = start + name.length + 1;
        var end = document.cookie.indexOf(";",start);
        if (end == -1){
          end = document.cookie.length;
        }
        return unescape(document.cookie.substring(start,end));
      } 
    }
    return '';
  }

　　

function delCookie(name){
       var exp = new Date();
       exp.setTime(exp.getTime() - 1);
       //获取cookie
       var cval=getCookie(name);
       if(cval!=null)
        document.cookie= name + "="+cval+";expires="+exp.toGMTString();
}