SOURCE

new Vue({
  el:'#app',
  data:{
    titile:'hello word!!!'
  },
  methods: {
    changeTitle: function (event) {
      // this.titile = event.target.value;
      this.titile = 'fuck';
    }
  }
});

<script src="https://cdn.jsdelivr.net/npm/vue">
</script>

<div id="app">  
  <input type="text" v-on:input="changeTitle"/>
<p>{{ titile }}</p>
</div>