004.Vue3入门，使用绑定属性时undefined和disabled用法

1、代码如下：

<template><div v-bind:id="myId1" v-bind:class="testCls">测试1</div><div v-bind:id="myId2" v-bind:title="testTitle">测试2</div><div :id="myId3" :class="testCls">测试2</div><button :disabled="isButtonDisabled">按钮</button>
</template><script>
export default {data() {return {testCls: "appclass",myId1: "appId1",myId2: "appId2",myId3: "appId3",title: undefined,isButtonDisabled: true}}
}
</script><style>
.appclass {color: red;font-size: 30px;
}</style>

2、效果如下：