[Vuejs]-How to read data from a Vue instance

You can access the data object of a vue instance by referring to instance.$data.
A vue instace like this:

var foo = new Vue({
el: "#app",
data() {
  return {
    bar: "inside data"
  };
},

can be accessed via foo.$data.bar.

Full example: https://codesandbox.io/s/4wwoxzow97