//app.js
  App({
    globalData: {
      addedToCart: false // 初始化全局状态
    },
    onLaunch: function () {
      //调用API从本地缓存中获取数据
      var logs = wx.getStorageSync('logs') || []
      logs.unshift(Date.now())
      wx.setStorageSync('logs', logs)
    },
    getUserInfo:function(cb){
      var that = this
      if(this.globalData.userInfo){
        typeof cb == "function" && cb(this.globalData.userInfo)
      }else{
        //调用登录接口
        wx.login({
          success: function () {
            wx.getUserInfo({
              success: function (res) {
                that.globalData.userInfo = res.userInfo
                typeof cb == "function" && cb(that.globalData.userInfo)
              }
            })
          }
        })
      }
    },
    globalData:{
      userInfo:null
    }
  })