react怎么实现表头固定

components/ScrollableTable/interface.tsx  import * as React from 'react'; export declare type AlignType = 'left' | 'center' | 'right'; export interface ColumnType {   align?: AlignType;   className?: string;   dataKey?: string;   fixed?: boolean;   title?: React.ReactNode;   width?: number;   render?: (value: any, record: any, index: number) => React.ReactNode; } export interface TableProps {   className?: string;   style?: React.CSSProperties;   columns?: ColumnType[];   dataSource?: any[];   width?: number;   height?: number; }  components/ScrollableTable/index.tsx  import React, { FunctionComponent, useRef } from 'react'; import { TableProps, ColumnType } from './interface'; import './index.less'; const ScrollableTable: FunctionComponent<any> = (props: TableProps) => {   const style: React.CSSProperties = props.style || {};   const maxHeight: string = props.width ? (props.height + 'px') : 'unset';   const columns: ColumnType[] = props.columns || [];   const dataSource: any[] = props.dataSource || [];   let maxWidth: number = 0;   if (props.width) style.width = props.width;   if (columns.length === 0) {     columns.push({       dataKey: 'key'     });   }   columns.forEach((column: ColumnType) => {     const width: number = column.width || 50;     maxWidth += width;   });   const fixedColumns: number[][] = getFixedColumns(columns);   const leftFixedColumns: number[] = fixedColumns[0];   const rightFixedColumns: number[] = fixedColumns[1];   const tableBody: any = useRef();   const handleScroll = (target: any) => {     const scrollLeft: number = target.scrollLeft;     const tableHeaders: any = target.parentElement.getElementsByClassName('st-table-header');     if (tableHeaders.length > 0) {       tableHeaders[0].scrollLeft = scrollLeft;     }   };   return (     <div       className={classNames('st-table-container', props.className)}       style={style}     >       <div className="st-table-header">         <table>           <colgroup>             {               renderCols(columns)             }           </colgroup>           <thead className="st-table-thead">             <tr>               {                 columns.map((column: ColumnType, index: number) => {                   const align: any = column.align || undefined;                   const title: React.ReactNode = column.title || '';                   const fixed: string = leftFixedColumns.includes(index) ? 'left' : (rightFixedColumns.includes(index) ? 'right' : '');                   const fixedClassName: string = fixed ? ('st-table-cell-fix-' + fixed) : '';                   return (                     <th                       key={index}                       className={classNames('st-table-cell', fixedClassName, column.className)}                       style={{textAlign: align}}                     >                       {title}                     </th>                   );                 })               }             </tr>           </thead>         </table>       </div>       <div         ref={tableBody}         className="st-table-body"         style={{maxHeight: maxHeight}}         onScroll={(e: any) => handleScroll(e.currentTarget)}       >         <table style={{width: maxWidth, minWidth: '100%'}}>           <colgroup>               {                 renderCols(columns)               }             </colgroup>             <tbody className="st-table-tbody">               {                 dataSource.map((record: any, index: number) => (                   <tr key={index} className="st-table-row">                     {                       renderCells(columns, leftFixedColumns, rightFixedColumns, record, index)                     }                   </tr>                 ))               }             </tbody>         </table>       </div>     </div>   ); }; function classNames(...names: (string | undefined)[]) {   const currentNames: string[] = [];   names.forEach((name: (string | undefined)) => {     if (name) currentNames.push(name);   });   return currentNames.join(' '); } function getFixedColumns(columns: ColumnType[]) {   const total: number = columns.length;   const leftFixedColumns: number[] = [];   const rightFixedColumns: number[] = [];   if (columns[0].fixed) {     for (let i = 0; i < total; i++) {       if (columns[i].fixed) {         leftFixedColumns.push(i);       } else {         break;       }     }   }   if (columns[total - 1].fixed) {     for (let i = total - 1; i >= 0; i--) {       if (columns[i].fixed) {         if (!leftFixedColumns.includes(i)) rightFixedColumns.push(i);       } else {         break;       }     }   }   return [leftFixedColumns, rightFixedColumns]; } function renderCols(columns: ColumnType[]) {   return columns.map((column: ColumnType, index: number) => {     const width: number = column.width || 50;     return (       <col         key={index}         style={{width: width, minWidth: width}}       />     );   }); } function renderCells(columns: ColumnType[], leftFixedColumns: number[], rightFixedColumns: number[], record: any, index: number) {   return columns.map((column: ColumnType, index: number) => {     const align: any = column.align || undefined;     const fixed: string = leftFixedColumns.includes(index) ? 'left' : (rightFixedColumns.includes(index) ? 'right' : '');     const className: string = classNames('st-table-cell', column.className, fixed ? ('st-table-cell-fix-' + fixed) : '');     const rawValue: any = (column.dataKey && column.dataKey in record) ? record[column.dataKey] : undefined;     let value: any = undefined;     if (column.render) {       value = column.render(rawValue, record, index);     } else {       value = (rawValue === undefined || rawValue === null) ? '' : String(rawValue);     }     return (       <td         key={index}         className={className}         style={{textAlign: align}}       >         {value}       </td>     );   }); } export default ScrollableTable;  components/ScrollableTable/index.less  .st-table-container {   border: 1px solid #f0f0f0;   border-right: 0;   border-bottom: 0;   font-size: 14px;   .st-table-header {     border-right: 1px solid #f0f0f0;     overflow: hidden;     table {       border-collapse: separate;       border-spacing: 0;       table-layout: fixed;       width: 100%;       thead.st-table-thead {         tr {           th.st-table-cell {             background: #fafafa;             border-bottom: 1px solid #f0f0f0;             border-right: 1px solid #f0f0f0;             color: rgba(0, 0, 0, .85);             font-weight: 500;             padding: 8px;             text-align: left;             &:last-child {               border-right: 0;             }           }         }       }     }   }   .st-table-body {     overflow: auto scroll;     border-bottom: 1px solid #f0f0f0;     border-right: 1px solid #f0f0f0;     table {       border-collapse: separate;       border-spacing: 0;       table-layout: fixed;       tbody.st-table-tbody {         tr.st-table-row {           td.st-table-cell  {             border-bottom: 1px solid #f0f0f0;             border-right: 1px solid #f0f0f0;             color: rgba(0, 0, 0, .65);             padding: 8px;             text-align: left;             &:last-child {               border-right: 0;             }           }           &:last-child {             td.st-table-cell  {               border-bottom: 0;             }           }         }       }     }   }   table {     .st-table-cell {       &.st-table-cell-fix-left {         background: #fff;         position: sticky;         left: 0;         z-index: 2;       }       &.st-table-cell-fix-right {         background: #fff;         position: sticky;         right: 0;         z-index: 2;       }     }   } }

views/Test/index.tsx import React, { FunctionComponent } from 'react'; import Page from '../../components/Page'; import ScrollableTable from '../../components/ScrollableTable'; import StoreProvider from '../../stores/products/context'; import './index.less'; const Test: FunctionComponent<any> = (props: any) => {   let records: any[] = [{     id: 1,     productName: '淡泰',     amount1: 198,     amount2: 200,     amount3: 205.5,     currency: '人民币',     ca: 'Amy'   }, {     productName: '方润',     amount1: 105.5,     amount2: 100,     amount3: 108,     currency: '港元',     ca: 'Baby'   }, {     productName: '医疗基金-1',     amount1: 153,     amount2: 150,     amount3: 155,     currency: '人民币',     ca: 'Emily'   }, {     productName: '医疗基金-2',     amount1: 302,     amount2: 300,     amount3: 290,     currency: '美元',     ca: 'Baby'   }, {     productName: '医疗基金-3',     amount1: 108.8,     amount2: 100,     amount3: 130,     currency: '人民币',     ca: 'Amy'   }, {     productName: '医疗基金-4',     amount1: 205,     amount2: 200,     amount3: 208,     currency: '美元',     ca: '吴丹'   }, {     productName: '医疗基金-5',     amount1: 315.5,     amount2: 300,     amount3: 280,     currency: '人民币',     ca: 'Baby'   }, {     productName: '医疗基金-6',     amount1: 109,     amount2: 95,     amount3: 106,     currency: '人民币',     ca: 'Emily'   }, {     productName: '恒大私募债',     amount1: 213,     amount2: 200,     amount3: 208,     currency: '港元',     ca: '吴丹'   }];   const totalRecord: any = {     productName: '合计',     amount1: {},     amount2: {},     amount3: {}   };   records.forEach((record: any) => {     const currency: string = record.currency;     ['amount1', 'amount2', 'amount3'].forEach((key: string) => {       const value: any = totalRecord[key];       if (!(currency in value)) value[currency] = 0;       value[currency] += record[key];     });   });   records.push(totalRecord);   const columns: any[] = [{     dataKey: 'productName',     title: '产品名称',     width: 90,     fixed: true   }, {     dataKey: 'amount1',     title: <React.Fragment>上周缴款金额<br/>（万）</React.Fragment>,     width: 140,     align: 'center',     className: 'amount',     render: calculateTotal   }, {     dataKey: 'amount2',     title: <React.Fragment>上周预约金额<br/>（万）</React.Fragment>,     width: 140,     align: 'center',     className: 'amount',     render: calculateTotal   }, {     dataKey: 'amount3',     title: <React.Fragment>待本周跟进金额<br/>（万）</React.Fragment>,     width: 140,     align: 'center',     className: 'amount',     render: calculateTotal   }, {     dataKey: 'currency',     title: '币种',     width: 80   }, {     dataKey: 'ca',     title: 'CA',     width: 80   }];   return (     <StoreProvider>       <Page         {...props}         title="销售统计"         className="test"       >         <div style={{padding: 15}}>           <ScrollableTable             width={window.innerWidth - 30}             height={196}             columns={columns}             dataSource={records}           />         </div>       </Page>     </StoreProvider>   ); }; function calculateTotal(value: any) {   if (value instanceof Object) {     const keys: any[] = Object.keys(value);     return (       <React.Fragment>         {           keys.map((key: string, index: number) => (             <span key={index}>               {`${value[key].toFixed(2)}万${key}`}             </span>           ))         }       </React.Fragment>     )   }   return value.toFixed(2); } export default Test;  views/Test/index.less  .st-table-container {   .st-table-body {     td.st-table-cell.amount {       padding-right: 20px !important;       text-align: right !important;       span {         display: block;       }     }   } }