下拉菜单
<jie-dropdown>
<jie-btn>Click Me!</jie-btn>
<jie-menu>
...
</jie-menu>
</jie-dropdown>
<script>
var dropdown = document.querySelector('jie-dropdown');
dropdown.addEventListener('select', function (e) {
// e.detail.selected
});
dropdown.open();
dropdown.close();
dropdown.toggle();
</script>