JSFiddle - React, Tailwind, and code Playground

HTML

<div id="app">

  <input @focus="onFocus" @blur="onBlur">

  <span v-show="focused">FOCUSED</span>

</div>

Babel + JSX

new Vue({
  el: '#app',
  data: {
    focused: false
  },
  methods: {
    onFocus() {
      this.focused = true
    },
    onBlur() {
      this.focused = false
    }
  }
});