Vue3获取元素DOM的两种方法

<template>
    <canvas ref="solarCanvas" id="solar" width="1300" height="900"></canvas>
</template>

<script setup>
import {  onMounted, ref } from 'vue'

const solarCanvas = ref(null)
onMounted(() => {
  console.log(solarCanvas.value)//HTMLCanvasElement{...}
})
</script>

<template>
    <canvas ref="solarCanvas" id="solar" width="1300" height="900"></canvas>
</template>

<script setup>
import {  onMounted, ref } from 'vue'

const solarCanvas = ref(null)
console.log(solarCanvas.value)//null
</script>

<template>
    <canvas id="solar" width="1300" height="900"></canvas>
</template>

<script setup>
import { nextTick, onMounted, ref } from 'vue'

onMounted(() => {
  const canvas = document.getElementById('solar')
  console.log(canvas)//HTMLCanvasElement{...}
})
</script>

document.querySelector(选择器)
document.getElementById(id选择器)
document.getElementsByClassName(class选择器)
....

<template>
  <div class="box">
    <h1 ref="divDom">这是一个测试样例</h1>
    <button ref="but">按钮</button>
  </div>
</template>
 
<script>
 
export default {
  data() {
    return {
    }
  },
  methods: {
    showThis(){
      // h1的实例对象 
      console.log(this);
      this.$refs.divDom.style.color='yellow'
      //引用到组件的实例之后，也可以调用组件上的 methods方法
      this.$refs.but.click();
    },
  },
}
</script>

<template>
    <div ref="divDom"></div>
</template>
 
<script setup>
    import { ref, getCurrentInstance } from 'vue';
    
    const divDom = ref(null);
    onMounted(()=>{
        console.log('获取dom元素',divDom)
    })
 
    // 获取页面的实例对象
    const pageInstance = getCurrentInstance();
    // 获取dom节点对象
    const tagDomObj = pageInstance.refs.divDom;
 
</script>