vue-element-admin项目使用Export2Excel导出excel样式修改，复杂表头
主要是在vue-element-admin自带Export2Excel模板的基础上进行修改，进行单元格宽度，边框，字体，颜色等设置以及复杂表头的处理
参考链接: /yinxingen/p/11052184.html.
1.安装xlsx-style:npm install --save xlsx-style，
import XLSX from "xlsx-style"报错：This relative module was not found: ./cptable in ./node_modules/xlsx-style@0.8.13@xlsx-style/dist/cpexcel.js，需要修改源码：
在\node_modules\xlsx-style\dist\cpexcel.js找到var cpt = require(’./cpt’ + ‘able’);并改成var cpt = cptable;
2.本地src/vendor/Export2Excel.js文件修改
import {saveAs } from "file-saver";// import XLSX from "xlsx";import XLSX from "xlsx-style";function generateArray(table) {var out = [];var rows = table.querySelectorAll("tr");var ranges = [];for (var R = 0; R < rows.length; ++R) {var outRow = [];var row = rows[R];var columns = row.querySelectorAll("td");for (var C = 0; C < columns.length; ++C) {var cell = columns[C];var colspan = cell.getAttribute("colspan");var rowspan = cell.getAttribute("rowspan");var cellValue = cell.innerText;if (cellValue !== "" && cellValue == +cellValue) cellValue = +cellValue;//Skip rangesranges.forEach(function (range) {if (R >= range.s.r &&R <= range.e.r &&outRow.length >= range.s.c &&outRow.length <= range.e.c) {for (var i = 0; i <= range.e.c - range.s.c; ++i) outRow.push(null);}});//Handle Row Spanif (rowspan || colspan) {rowspan = rowspan || 1;colspan = colspan || 1;ranges.push({s: {r: R,c: outRow.length},e: {r: R + rowspan - 1,c: outRow.length + colspan - 1}});}//Handle ValueoutRow.push(cellValue !== "" ? cellValue : null);//Handle Colspanif (colspan)for (var k = 0; k < colspan - 1; ++k) outRow.push(null);}out.push(outRow);}return [out, ranges];}function datenum(v, date1904) {if (date1904) v += 1462;var epoch = Date.parse(v);return (epoch - new Date(Date.UTC(1899, 11, 30))) / (24 * 60 * 60 * 1000);}function sheet_from_array_of_arrays(data, opts) {var ws = {};var range = {s: {c: 10000000,r: 10000000},e: {c: 0,r: 0}};for (var R = 0; R != data.length; ++R) {for (var C = 0; C != data[R].length; ++C) {if (range.s.r > R) range.s.r = R;if (range.s.c > C) range.s.c = C;if (range.e.r < R) range.e.r = R;if (range.e.c < C) range.e.c = C;var cell = {v: data[R][C]};// 如果单元格所在的值为空，让其值为“——”，否则下面设置的边框对其不生效if (cell.v == null) {cell.v = "——";}var cell_ref = XLSX.utils.encode_cell({c: C,r: R});if (typeof cell.v === "number") cell.t = "n";else if (typeof cell.v === "boolean") cell.t = "b";else if (cell.v instanceof Date) {cell.t = "n";cell.z = XLSX.SSF._table[14];cell.v = datenum(cell.v);} else cell.t = "s";ws[cell_ref] = cell;}}if (range.s.c < 10000000) ws["!ref"] = XLSX.utils.encode_range(range);return ws;}function Workbook() {if (!(this instanceof Workbook)) return new Workbook();this.SheetNames = [];this.Sheets = {};}function s2ab(s) {var buf = new ArrayBuffer(s.length);var view = new Uint8Array(buf);for (var i = 0; i != s.length; ++i) view[i] = s.charCodeAt(i) & 0xff;return buf;}export function export_table_to_excel(id) {var theTable = document.getElementById(id);var oo = generateArray(theTable);var ranges = oo[1];/* original data */var data = oo[0];var ws_name = "SheetJS";var wb = new Workbook(),ws = sheet_from_array_of_arrays(data);/* add ranges to worksheet */// ws['!cols'] = ['apple', 'banan'];ws["!merges"] = ranges;/* add worksheet to workbook */wb.SheetNames.push(ws_name);wb.Sheets[ws_name] = ws;var wbout = XLSX.write(wb, {bookType: "xlsx",bookSST: false,type: "binary"});saveAs(new Blob([s2ab(wbout)], {type: "application/octet-stream"}),"test.xlsx");}// 主要修改内容在这里export function export_json_to_excel({title, // 新增的参数，表格标题multiHeader = [],header,data,filename,merges = [],autoWidth = true,bookType = "xlsx"} = {}) {/* original data */filename = filename || "excel-list";data = [...data];data.unshift(header);for (let i = multiHeader.length - 1; i > -1; i--) {data.unshift(multiHeader[i]);}data.unshift(title); // 表格标题var ws_name = "SheetJS";var wb = new Workbook(),ws = sheet_from_array_of_arrays(data);if (merges.length > 0) {if (!ws["!merges"]) ws["!merges"] = [];merges.forEach(item => {ws["!merges"].push(XLSX.utils.decode_range(item));});}// 设置单元格宽度if (autoWidth) {/*设置worksheet每列的最大宽度*/const colWidth = data.map(row =>row.map(val => {/*先判断是否为null/undefined*/if (val == null || val == undefined) {return {wch: 10};} else if (val.toString().charCodeAt(0) > 255) {/*再判断是否为中文*/return {wch: val.toString().length * 2};} else {return {wch: val.toString().length * 1.5};}}));/*以主表第二行为初始值，因为我的第一行是表格标题，会比较长，所以以主表第二行为初始值*/let result = colWidth[1];for (let i = 1; i < colWidth.length; i++) {for (let j = 0; j < colWidth[i].length; j++) {if (result[j]["wch"] < colWidth[i][j]["wch"]) {result[j]["wch"] = colWidth[i][j]["wch"];}}}ws["!cols"] = result;}/* add worksheet to workbook */wb.SheetNames.push(ws_name);wb.Sheets[ws_name] = ws;var dataInfo = wb.Sheets[wb.SheetNames[0]];// 设置单元格框线const borderAll = {top: {style: "thin"},bottom: {style: "thin"},left: {style: "thin"},right: {style: "thin"}};// 给所有单元格加上边框，内容居中，字体，字号，标题表头特殊格式部分后面替换for (var i in dataInfo) {if (i == "!ref" ||i == "!merges" ||i == "!cols" ||i == "!rows" ||i == "A1") {} else {dataInfo[i + ""].s = {border: borderAll,alignment: {horizontal: "center",vertical: "center"},font: {name: "微软雅黑",sz: 10}};}}// 设置表格样式const arrabc = ["A","B","C","D","E","F","G","H","I","J","K","L","M","N","O","P","Q","R","S","T","U","V","W","X","Y","Z"]// 给标题、表格描述信息、表头等部分加上特殊格式arrabc.some(function (v) {for (let j = 1; j < multiHeader.length + 3; j++) {const _v = v + jif (dataInfo[_v]) {dataInfo[_v].s = {};// 标题部分A1-Z1if (j == 1) {dataInfo[v + j].s = {font: {name: "微软雅黑",sz: 12,color: {rgb: "000000"},bold: true,italic: false,underline: false},alignment: {horizontal: "center",vertical: "center"}};} else {// 表头部分,根据表头特殊格式设置if (multiHeader.length == 0) {// multiHeader.length = 0 时表头没有合并单元格，表头只占1行A2-Z2const fv = v + (multiHeader.length + 2)dataInfo[fv].s = {border: borderAll,font: {name: "微软雅黑",sz: 11,bold: true},alignment: {horizontal: "center",vertical: "center"},fill: {fgColor: {rgb: "f0f0f0"},},}} else if (multiHeader.length == 1) {// multiHeader.length = 0 时表头有合并单元格，表头只占2行A2-Z2，A3-Z3，这是没有描述信息只有表头合并的dataInfo[v + j].s = {border: borderAll,font: {name: "微软雅黑",sz: 11,},alignment: {horizontal: "center",vertical: "center"},fill: {fgColor: {rgb: "f0f0f0"}},}} else {// multiHeader.length = 0 时表头有合并单元格，表头多行dataInfo[v + j].s = {border: borderAll,font: {name: "微软雅黑",sz: 9,},alignment: {horizontal: "left",vertical: "center"}}}}// multiHeader.length + 2 是表头的最后1行dataInfo[v + (multiHeader.length + 2)].s = {border: borderAll,font: {name: "微软雅黑",sz: 10,},alignment: {horizontal: "center",vertical: "center"},fill: {fgColor: {rgb: "f0f0f0"}},}}}});var wbout = XLSX.write(wb, {bookType: bookType,bookSST: false,type: "binary"});saveAs(new Blob([s2ab(wbout)], {type: "application/octet-stream"}),`${filename}.${bookType}`);}
3.调用Export2Excel.js，根据实际需要给title, multiHeader header, data,merges等参数赋值，复杂多级表头主要在multiHeader处理，multiHeader 是数组，可以添加多个数组
// 调用handleDownload() {import("@/vendor/Export2Excel").then(excel => {const title = [this.title, "", ""];const header = ["序号", "***", "***"];const filterVal = ["index", "***", "***"];const merges = ["A1:C1"];const query = {pageNum: 1,pageSize: this.total};getData(query).then(res => {const list = res.data.list;const data = this.formatJson(filterVal, list);excel.export_json_to_excel({title,header,merges,data,filename: this.title,autoWidth: this.autoWidth,bookType: this.bookType});});});},formatJson(filterVal, jsonData) {jsonData.map((row, index) => {row.index = index + 1;});return jsonData.map(v =>filterVal.map(j => {return v[j];}));}},
// 多级表头const multiHeader = [["title", "", "", "", "", "", "", ""],["日期",this.time,"**","**","**","**","**","**",],["联系人","张三","**","**","联系电话","123456789*","**","**",]];
tip:这里表头部分如果不能满足所有表格，可以根据实际需要拷贝多个Export2Excel.js文件调整表头部分，根据实际需要引入不同的Export2Excel.js文件
