一文学会什么是vue.nextTick()

<template>
  <div>
    <button ref="btn" @click="handleBtn()">{{ message }}</button>
  </div>
</template>
<script>
export default {
  data(){
    return{
      message:'这个是原始值'
    }
  },
  methods:{
    handleBtn:function(){
    let that=this
    that.message='修改后的值'
    console.log(that.$refs.btn.innerText);//这里输出的还是原始值
  }
  }
}
</script>
<style>
</style>

<template>
  <div>
    <button ref="btn" @click="handleBtn()">{{ message }}</button>
  </div>
</template>
<script>
export default {
  data(){
    return{
      message:'这个是原始值'
    }
  },
  methods:{
    handleBtn:function(){
    let that=this
    that.message='修改后的值'
    this.$nextTick(function(){
      console.log(that.$refs.btn.innerText);  //这里输出的是修改后的值
    })
  }
  }
}
</script>
<style>
</style>

<template>
  <div>
    {{ message }}
    <button @click="changeText()">测试</button>
  </div>
</template>
<script>
export default {
  data() {
    return {
      message: "这个是原始值",
    };
  },
  methods: {
    changeText () {
      let that = this;
      this.message = "这是修改后的值";
      that.$nextTick(function(){
        let txt=document.getElementById('btn').innerText
        console.log(txt);
        txt==='这个是原始值'? console.log('data的值发生改变时DOM的值没有立即更新') : console.log('data的值发生改变时DOM的值立刻更新了');
      })
    },
  },
};
</script>
<style>
</style>