JSFiddle - React, Tailwind, and code Playground

HTML

<div id="app">
  <ul>
    <li v-for="item in items" ref="its" :key="item">
      {{item}}
    </li>
  </ul>
  <button @click="add">add</button>
  <button @click="set">set</button>
</div>

JavaScript

let id = 5
new Vue({
  data: {
    items: [1, 2, 3]
  },
  methods: {
    add() {
      this.$refs.its = null
      this.items.unshift(id++)
    },
    set() {
      console.log(this.$refs.its)
      this.$refs.its[0].style.border = "1px solid red"
    }
  }
}).$mount('#app')