[Vuejs]-Store the elements of an object using vue.js

data() {
  return {
    user: {
      userName: "",
      userAge: ""
    },
  };
},

methods: {
  saveUserName: function() {
    this.user.userName = this.newUserName;
    this.$refs.userNameModal.hideModal();
    this.saveUser();
  },

  saveUserAge: function() {
    this.user.userAge = this.newUserAge;
    this.$refs.userAgeModal.hideModal();
    this.saveUser();
  },

  saveUser: function() {
    this.$session.set('userDetails', this.user);
  },
},

beforeMount: function() {
  if (this.$session.exists('userDetails')) {
    this.user = this.$session.get('userDetails');
    console.log("userDetails", this.user)
  }
}