Edit in JSFiddle

  const vm = new Vue({
    el: "#app",
    data: {a: ""},
    created: function() { this.reset() },
    watch: {
      a: function() { this.reset() },
    },
    methods: {
      reset: _.debounce(function() {
        document.location = "/"
      }, 1000 * 5),
    },
  })
<div id="app">
  <div class="form-horizontal">
    <div class="form-group">
      <label class="col-md-2 control-label">入力</label>
      <div class="col-md-10">
        <input class="form-control" v-model="a" />
      </div>
    </div>
  </div>
</div>