2018-08-24

<div id="app">
    <p ref="a">{{a}}</p>
    <button @click="foo">change</button>
</div>
<script>
    var app = new Vue({
        el: "#app",
        data: {
            a: 333
        },
        methods: {
            foo() {
                this.a = this.a+1;
                Vue.nextTick().then(function () {
                    console.log(app.$refs.a.innerHTML);
                })
                console.log(app.$refs.a.innerHTML);
            }
        }
    })
</script>

点击后输出：
333 //在视图更新前就输出了
334 //在视图更新后才输出