<template>

  <div id="app">

    <div ref="box"></div>

    <button @click="changeColor">改变</button>

  </div>

</template>

<script>

export default {

  name: "app",

  data() {

    return {

    };

  },

  methods:{

    changeColor() {

      this.$refs.box.style.color = 'red'

    }

  }

};

</script>

<style>

</style>