如何声明localStorage变量以避免引用错误

我发现了“localStorage” this post

当我只需要保存用户名时,我没有任何错误,但是后来,我添加了一个'grd'变量来保存,我得到了这个错误:

[Vue warn]: Error in created hook: "ReferenceError: grd is not defined"

页面加载时,我就是这样获取数据的:

var name = localStorage.getItem(name);
var grade = localStorage.getItem(grd);
if (name !== null){
  this.user = name;
}
if (grade !== null){
  this.userGrade = grade;
}

我就是这样保存数据的:

localStorage.setItem(name, '');
localStorage.setItem(grd, '');

我正在使用虚拟用户.js在本项目中