从零开始使用vue2+element搭建后台管理系统（实现导出excel表格的功能）

首先参阅了以下文档：

https://panjiachen.gitee.io/vue-element-admin-site/zh/feature/component/excel.html#excel-%E5%AF%BC%E5%87%BA

https://blog.csdn.net/weixin_42028153/article/details/124804841

核心思想：抄一下vue-element-admin这个很棒的开源集成后台管理系统中所提供的excel功能

首先引入依赖：

npm install xlsx file-saver -S
npm install script-loader -S -D

然后在utils文件夹下新增Export2Excel.js文件（也可以自己找地方建）：

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

function generateArray(table) {
  console.log(XLSX);
  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]);
  }
  console.log(XLSX, "===XLSX");
  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}`
  );
}

（以上代码是vue-element-admin封装的）

然后在需要导出表格的页面上补充相关代码，首先是增加一个按钮：

<el-row type="flex" class="row-bg" justify="end">
        <el-button
          :loading="downloadLoading"
          icon="el-icon-download"
          circle
          @click="handleDownload"
          size="mini"
        ></el-button>
      </el-row>

css随便写一下：

.row-bg {
  padding: 8px;
  background-color: #f9fafc;
}

页面效果：

methods里新增两个方法：

handleDownload() {
      this.downloadLoading = true;
      import("@/utils/Export2Excel").then((excel) => {
        console.log(excel, "excel");
        const tHeader =
          this.tableHeader && this.tableHeader.map((item) => item.name);
        const filterVal =
          this.tableHeader && this.tableHeader.map((item) => item.id);
        const list = this.tableData;
        const data = this.formatJson(filterVal, list);
        excel.export_json_to_excel({
          header: tHeader,
          data,
          filename: "导出表格",
        });
        this.downloadLoading = false;
      });
    },
    formatJson(filterVal, jsonData) {
      return jsonData.map((v) =>
        filterVal.map((j) => {
          return v[j];
        })
      );
    },

此刻点击表格右上方的下载按钮发现报错utils找不到，因此用到了第二篇参考文档：

不得不说it技术更新迭代的速度十分快，于是参照文档里的两个命令，降低相关依赖版本：

npm install --save [email protected]
npm install --save [email protected]

清理掉node_modules文件夹，重新下一波依赖，启动项目后，点击按钮就可以下载了：

 至此，简单的表格导出功能就实现了，让我们感谢无私奉献、热爱技术的大佬们！！

如果需要导出多层表头，文档一的集成方案中也提供了，可以进行参阅学习以及COPY。