JSFiddle - React, Tailwind, and code Playground

HTML

<script src="https://unpkg.com/vue@2.0.0/dist/vue.js"></script>
<div id="example">
  <p>名前 {{ name }}</p>
  <p v-show="!isValid">
    名前を入力してください
  </p>
</div>

JavaScript

var vm = new Vue({
  el: '#example',
  data: {
    name: '',
  },
  computed: {
    isValid: function () {
      return this.name.length > 0;
    }
  }
});
window.vm = vm;