uniapp怎么判断是否登录

global.isLogin = function(){
 try{
  var id  = uni.getStorageSync('id');
  var name = uni.getStorageSync('name');
 }catch(e){
  //TODO handle the exception
 }
 if(id == '' || name == ''){
  return false;
 }else{
  return [id, name];
 }};

var res = global.isLogin();
  if(!res){
   uni.showModal({
    title:'请登录',
    content:"请登录",
    success:function(){
     uni.navigateTo({
      url:"/pages/login"
     });
    }
   })
  }

uni.setStorageSync('id', res.data.id);
uni.setStorageSync('name', res.data.name);