SOURCE

console.log('Vue: ');
console.log(Vue);

new Vue({
    el: '#app',
    data: function() {
    return { visible: false }
    }
})

<script src="https://cdn.bootcdn.net/ajax/libs/vue/2.6.9/vue.min.js
"></script>

<!-- 引入样式 -->
<link rel="stylesheet" href="https://unpkg.com/element-ui/lib/theme-chalk/index.css">
<!-- 引入组件库 -->
<script src="https://unpkg.com/element-ui/lib/index.js"></script>


<div id="app">
    <el-button @click="visible = true">Button</el-button>
    <el-dialog :visible.sync="visible" title="Hello world">
        <p>Try Element</p>
    </el-dialog>
</div>