SOURCE

new Vue({
  el: '#app',
  data: {
    name: 'bofa',
    counter: 0,
    secondCounter: 0
  },
  computed: {
    output: function() {
      return this.counter > 5 ? '大于5': '小于5';
    }
  },
  watch: {
    counter: function(value) {
      var vm = this;
      setTimeout(function() {
        vm.counter = 0;
      },2000)
    }
  },
  methods: {
    result: function() {
      return this.counter > 5 ? '大于5': '小于5';
    }
  }
})

<script src="https://cdn.jsdelivr.net/npm/vue/dist/vue.js">
</script>
<div id="app">
  <p>
    <input type="text" v-model="name">
  </p>
  <p>
    {{ name }}
  </p>
  <button v-on:click="counter++">
    Increase
  </button>
  <button v-on:click="counter--">
    Decrease
  </button>
  <button v-on:click="secondCounter++">
    Increase Second
  </button>
  <p>
    COnuter: {{ counter }} | {{ secondCounter }}
  </p>
  <p>
    Result: {{ result() }} | {{ output }}
  </p>
</div>