SOURCE

new Vue({
    el:"#app",
    data:{
        title:"hello world!",
        finishLink:'<a href="https://www.baidu.com">百度</a>'
    },
    methods:{
        changeTitle:function(ev){
            this.title=ev.target.value            
        },
        sayHello:function(){
            this.title="hello123";
            return this.title;
        }
    }
});

<script src="https://cdn.jsdelivr.net/npm/vue"></script>
<div id="app">
    <input type="text" v-on:input="changeTitle" />
    <h2>{{title}}</h2>
    <p>{{sayHello()}}</p>
</div>