1.   //v-if将dom直接移除
    2.   //v-show通过display: none
    3.   const app = Vue.createApp({
    4.     data() {
    5.       return {
    6.         show: false,
    7.         conditionOne: true,
    8.         conditionTwo: false,
    9.       }
    10.     },
    11.     template: `
    12.       <div v-if="show">Hello World</div> 
    13.       <div v-if="conditionOne">if</div>
    14.       <div v-else-if="conditionTwo">elseif</div>
    15.       <div v-else>else</div>
    16.       <div v-show="show">Bye World</div>
    17.     `
    18.   });
    20.   const vm = app.mount('#root');

    conditionOne: true,
    conditionTwo: true,
    或者
    conditionOne: true,
    conditionTwo: false,
    显示：if
    conditionOne: true,
    conditionTwo: false,
    显示：elseif
    conditionOne: false,
    conditionTwo: false,
    显示：else