解决elementui-plus使用el-table的合计功能时横向滚动条显示在了合计上方

需求：如何在el-table使用合计功能时让横向滚动条显示在最下方

分析:其实el-table一共分为三部分：el-table__header-wrapper、el-table__body-wrapper和el-table__footer-wrapper 滚动条是一直显示在el-table__body-wrapper上的我们只需要把放在el-table__body-wrapper上的滚动条显示在el-table__footer-wrapper上再开启滚动监听就可以了

1、先隐藏原本的滚动条并将合计的滚动条打开：

:deep(.el-table__body-wrapper .el-scrollbar__bar) {

  display: none !important;

}

:deep(.el-table__footer-wrapper) {

  overflow: auto;

}

2、监听el-table__footer-wrapper的滚动

        在onMounted中绑定监听事件

<el-table v-loading="loading"
  :data="tableData"
  :row-key="rowKey"
  show-summary
  border
  ref="multipleTableRef"></el-table>

const multipleTableRef: any = ref<HTMLElement | null>(null);

let tableFooterBody: HTMLElement | null = null;
const syncScroll = () => {
  if (!tableFooterBody) return;
  const scrollLeft = tableFooterBody.scrollLeft;
  const tableHeaderBody = multipleTableRef.value?.$el.querySelector('.el-table__header-wrapper') as HTMLElement;
  const tableBodyScrollbar = multipleTableRef.value?.$el.querySelector('.el-table__body-wrapper .el-scrollbar__wrap') as HTMLElement;

  if (tableHeaderBody) tableHeaderBody.scrollLeft = scrollLeft;
  if (tableBodyScrollbar) tableBodyScrollbar.scrollLeft = scrollLeft;
};

onMounted(() => {
  tableFooterBody = multipleTableRef.value?.$el.querySelector('.el-table__footer-wrapper') as HTMLElement;
  if (tableFooterBody) {
    tableFooterBody.addEventListener('scroll', syncScroll);
  }
});

// 卸载时移除事件防止内存泄漏
onUnmounted(() => {
  if (tableFooterBody) {
    tableFooterBody.removeEventListener('scroll', syncScroll);
  }
});

这里边注意因为el-table__footer-wrapper用的是el-scrollbar组件，所以 tableBody 实际上不是直接可滚动的元素，而是 el-scrollbar 里面的 .el-scrollbar__wrap 负责滚动。