设置、获取、清除cookie

cookie是一个个键值对（“键=值”的形式）加上分号空格隔开组合而成， 形如： "name1=value1; name2=value2; name3=value3"

F12输入document.cookie 然后enter可看到cookie
或者在Application中可以看到cookie和localstorage等

    //设置cookie
    setCookie: function(cname, cvalue, exdays) {
      var d = new Date();
      d.setTime(d.getTime() + exdays * 24 * 60 * 60 * 1000);
      var expires = "expires=" + d.toUTCString();
      console.info(cname + "=" + cvalue + "; " + expires);
      document.cookie = cname + "=" + cvalue + "; " + expires;
      console.info(document.cookie);
    },
    //获取cookie
    getCookie: function(cname) {
      var name = cname + "=";
      var ca = document.cookie.split(";");
      console.log("获取cookie,现在循环");
      for (var i = 0; i < ca.length; i++) {
        var c = ca[i];
        console.log(c);
        while (c.charAt(0) == " ") c = c.substring(1);
        if (c.indexOf(name) != -1) {
          return c.substring(name.length, c.length);
        }
      }
      return "";
    },
    // 删除cookie
    delCookie:function(cname){
       this.setCookie(cname, ' ', -1);
    }