vue导出excel多层表头的实现方案详解

npm install xlsx file-saver -S
npm install xlsx

<script src="https://cdn.staticfile.net/FileSaver.js/2014-11-29/FileSaver.min.js"></script> <script src="https://cdn.staticfile.net/xlsx/0.18.2/xlsx.full.min.js"></script>

import { saveAs } from 'file-saver'
import XLSX from 'xlsx'
// import * as XLSX from 'xlsx/xlsx.mjs'
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 ranges
      ranges.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 Span
      if (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 Value
      outRow.push(cellValue !== "" ? cellValue : null);
 
      //Handle Colspan
      if (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) {
  console.log(XLSX,"==============XLSX")
  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]
      };
      if (cell.v == null) continue;
      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")
}
 
export function export_json_to_excel({
  multiHeader = [],
  header,
  data,
  merges,
  filename,
  autoWidth = true,
  bookType = 'xlsx'
} = {}) {
  /* original data */
  filename = filename || 'excel-list'
  data = [...data]
    data.unshift(header);
    // console.log(multiHeader,"data")
    if(multiHeader.length > 0){
      for (let i = multiHeader.length - 1; i > -1; i--) {
        data.unshift(multiHeader[i])
      }
    }else{
        data.unshift(multiHeader)
    }
  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))
    })
  }
 
  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) {
        return {
          'wch': 10
        };
      }
      /*再判断是否为中文*/
      else if (val.toString().charCodeAt(0) > 255) {
        return {
          'wch': val.toString().length * 2
        };
      } else {
        return {
          'wch': val.toString().length
        };
      }
    }))
    /*以第一行为初始值*/
    let result = colWidth[0];
    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;
  }
  
 /**
   * 自定义
   */
//  var dataInfo = wb.Sheets[wb.SheetNames[0]];
//  let arr = [//    "A1",//    "B1",//    "C1",//    "D1",//    "E1",//    "F1",//    "G1",//    "H1",//    "I1",//    "J1",//    "K1",//    "L1",//    "M1",//    "N1",//    "O1",//    "P1",//    "Q1",//    "R1",//    "S1",//    "T1",//    "U1",//    "V1",//    "W1",//    "X1",//    "Y1",//    "Z1"//  ];

//  let style = {
//    font: {
//      color: { rgb: "000000" },
//      bold: true
//    },
//    alignment: {
//      horizontal: "center",
//      vertical: "center"
//    }
//  };
//  for (var i = 0; i < header.length; i++) {
//    dataInfo[arr[i]].s = style;
//  }


  /* add worksheet to workbook */
  wb.SheetNames.push(ws_name);
  wb.Sheets[ws_name] = ws;
 
  var wbout = XLSX.write(wb, {
    bookType: bookType,
    bookSST: false,
    type: 'binary'
  });
  saveAs(new Blob([s2ab(wbout)], {
    type: "application/octet-stream"
  }), `${filename}.${bookType}`);
}

import { 
    export_json_to_excel 
    
} 
from "@/assets/js/Export2Excel";

//上层表头
              const multiheader = [
                ['大标题','','','','','',''],
                ['小标题1','小标题2','','小标题3:','','','小标题4']
              ] // 前两行的表头数据，二维数组，不够的用空白补全
              //二级表头
              const tHeader = [
                '序号',
                'A',
                'B',
                'C',
                'D',
                'E',
                'F'
              ] // 最后一行的表头数据
              //字段属性
              const filterVal = ['index0','index1','index2','index3','index4','index5','index6']
              //这里要注意 tHeader  和 filterVal 的数组长度一定要相等，否则会报错
              //设置要合并的单元格
              const mergers = [
                'A1:G1',
                'B2:C2',
                'D2:F2'
              ]
              var fromData = res.data              
              const data = this.formatJson(filterVal, fromData)
              export_json_to_excel({
                multiHeader: multiheader,
                header: tHeader,
                data,
                merges: mergers,
                filename: 'excel文件名称',
                autoWidth: true,
                bookType: 'xlsx'
              })