键盘事件
```html
<div id="app">
<div>
<p>按下回车键触发事件</p>
<input type="text" @keyup.enter="keyEvent" placeholder="按下回车键">
</div>
<div>
<p>按下alt+回车键触发事件</p>
<input type="text" @keyup.alt.enter="keyEvent" placeholder="按下alt+回车键">
</div>
</div>
```
```javascript
new Vue({
el: '#app',
methods: {
keyEvent() {
console.log('xxx')
}
}
})
```