前言

最近需要实现将json数据导出到excel中，研究了一下，查了一些文章，在这里梳理一下常见的用法。
需要借助SheetJS里面的几个插件

官方文档

基本用法

安装

 npm install xlsx

导出数据

import * as XLSX from 'xlsx';

// 将数据导出到excel表格里
handleDownload() { 
    // 需要导出的数据
    const exportArr = [
        {  key: 1, name: 'zhangsan', value: '123' },
        {  key: 2, name: 'lisi', value: '456' }
    ];

    // 自定义下载的header，注意是数组中的数组哦
    const Header = [['编号', '姓名', '电话']];

    // 将JS数据数组转换为工作表。
    const headerWs = XLSX.utils.aoa_to_sheet(Header);
    const ws = XLSX.utils.sheet_add_json(headerWs, exportArr, { skipHeader: true, origin: 'A2'});

    /* 新建空的工作表 */
    const wb = XLSX.utils.book_new();

    // 可以自定义下载之后的sheetname
    XLSX.utils.book_append_sheet(wb, ws, 'sheetName');

    /* 生成xlsx文件 */
    XLSX.writeFile(wb, '下载.xlsx');
}

{skipHeader: true, origin: 'A2'} ：跳过页眉，数据从A2开始

导出多个sheet

基于上面的例子

// 可以自定义下载之后的sheetname，用于添加sheet
XLSX.utils.book_append_sheet(wb, ws, 'sheet1');
XLSX.utils.book_append_sheet(wb, ws, 'sheet2');

处理多级表头

参考文章：使用js-xlsx插件导出多级表头excel

示例

mergeHeader() { 
	let tableData = [
	    { 
	        date: '2016-05-03',
	        name: '王小虎',
	        province: '上海',
	        city: '普陀区',
	        address: '上海市普陀区金沙江路 1518 弄',
	        zip: 200333
	    },
	    { 
	        date: '2016-05-02',
	        name: '王小虎',
	        province: '上海',
	        city: '普陀区',
	        address: '上海市普陀区金沙江路 1518 弄',
	        zip: 200333
	    }
	];
	import('./Export2Excel').then(excel => { 
	    const multiHeader =
	                [
	                    ['日期', '配送信息', '', '', '', ''], // 第一行
	                    ['', '姓名', '地址', '', '', ''] // 第二行
	                ]; // 前两行的表头数据，二维数组，不够的用空白补全
	    const header = ['', '', '省份', '市区', '地址', '邮编']; // 最后一行的表头数据
	    const filterVal = ['date', 'name', 'province', 'city', 'address', 'zip'];
	    const list = tableData;
	    const data = this.formatJson(filterVal, list);
	    const merges = ['A1:A3', 'B1:F1', 'B2:B3', 'C2:F2']; // 合并单元格的数据，如何合并参考上面图片的蓝色背景部分
	    excel.export_json_to_excel({ 
	        multiHeader,
	        header,
	        merges,
	        data
	    });
	});
},
// 格式化json数据
formatJson(filterVal, jsonData) { 
    return jsonData.map(v => filterVal.map(j => { 
        return v[j];
    }));
}

Export2Excel.js
文章里有链接，这是代码

/* eslint-disable */
import {  saveAs } from "file-saver";
import * as XLSX from "xlsx";

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) { 
  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,
  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]);
  }

  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,
          };
        } 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,
          };
        }
      })
    );
    /*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;
  }

  /* 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}`
  );
}

结果：

备注：

• 尽量不要前端导出，因为有点问题就打断点调试了一下，处理数据时会进行大量的循环，如果数据比较多可能会出问题。
• 需要下载 XLSX 和 file-saver 这两个依赖，Export2Excel会用到这两个依赖

使用注意：

• multiHeader 存储多级表头数据，类型是数组，里面的元素还是数组。空白的地方要用空字符串占位，要用于合并，不要啥都不填
• filterVal 保存要导出的列的key值，要与表头一一对应
• merges 合并单元格的数据，例如：'A1:A3' 合并A1列合并3行；这是excel表的公式，不清楚的自己百度一下。