微信小程序如何修改本地缓存key中单个数据的详

{no: "1635050601", name: "张三", sex: "", email: "123@qq.", classid: "100000-1602", …}
classid:"100000-1602"
classname:"16级PHP2"
departmentid:"100000"
departmentname:"软件学院"
name:"张三"
no:"1635050601"
sex:""

 //表单提交
 formSubmit: function (e) {
 console.log(e.detail.value);
 var pwd = e.detail.value.pwd;
 var email = e.detail.value.email;
 if (pwd == '') {
  wx.showToast({
  title: '密码不能为空',
  icon: 'none',
  duration: 1000,
  })
 }else if (email == '') {
  wx.showToast({
  title: '邮箱不能为空',
  icon: 'none',
  duration: 1000,
  })
 }else {
  //post方式提交
  wx.request({
  url: app.globalData.url.bindemail,
  method: "POST",
  data: {
   no: this.data.no,
   pwd: pwd,
   email: email
  },
  header: {
   "Content-Type": "application/x--form-urlencoded"
  },
  suess: function (res) {
   // console.log(res);
   if(res.data.error == true){
   wx.showToast({
    title: res.data.msg,
    icon: 'none',
    duration: 1000,
   })
   }else{
   //修改email
   var _student = wx.getStorageSync('student');
   _student.email = email;
   wx.setStorageSync('student', _student);
   
   wx.showToast({
    title: res.data.msg,
    icon: 'suess',
    duration: 2000,
    suess: function () {
    setTimeout(function () {
     wx.reLaunch({
     url: '../myinfo/myinfo',
     })
    }, 2000)
    }
   })
   }
  },
  })
 }
 },

//修改email
   var _student = wx.getStorageSync('student');
   _student.email = email;
   wx.setStorageSync('student', _student);