[Vuejs]-Vue.js does not show symbols

There are two ways to use the data property in vue

This is used when you are using vue in a root Vue instance

new Vue({
  el: "#app",
  data: {
      name: 'Vue !'
    }

});

This is used when you are using vue components

new Vue({
  el: "#app",
  data() {
    return {
      name: 'Vue !'
    }
  }
});

Are you using components?