iter(g208): multiSelect 支持一键清空

packages/skin/ui/src/multiSelect.ts

@@ -54,7 +54,9 @@ export function multiSelect(props: MultiSelectProps): HTMLElement {
   box.append(tagWrap, input); // 标签区在前、输入框在后，横向排布
   const list = h('ul', { class: 'ua-multiselect-list', role: 'listbox', 'aria-multiselectable': 'true' }) as HTMLElement;
   const pop = h('div', { class: () => `ua-multiselect-pop${open() ? ' ua-open' : ''}${place() === 'top' ? ' is-flip' : ''}` }, list) as HTMLElement;
-  const root = h('div', { class: () => `ua-multiselect${open() ? ' ua-open' : ''}` }, box, pop) as HTMLElement;
+  const clearBtn = h('button', { type: 'button', class: 'ua-select-clear', 'aria-label': '清空所选', hidden: true, onClick: (e: Event) => { e.stopPropagation(); update([]); input.focus(); } }, '×') as HTMLElement; // 复用 select 清空钮样式；阻止冒泡免得清完又展开
+  const root = h('div', { class: () => `ua-multiselect${open() ? ' ua-open' : ''}` }, box, props.clearable ? clearBtn : null, pop) as HTMLElement;
+  effect(() => { clearBtn.hidden = !value().length; }); // 有值才显示（clearable 未开时按钮根本不挂载）
 
   /*** 重绘标签区与候选：标签带删除钮，候选带勾选态与禁用态 ***/
   const render = (): void => {