使用`js-xlsx`导出一级或多级表头表格

简述

此方法来源于vue-element-admin框架中的本地到出表格功能，以下记录只是将方法及规律整理一下。

起步

安装 xlsx

yarn add xlsx@0.14.1 file-saver
yarn add script-loader -D

引入Export2Excel.js

新建一个vendor文件夹，下面放置Export2Excel.js,代码如下：

/* eslint-disable */
import { saveAs } from 'file-saver'
import 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
        };
      }
      /*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;
  }

  /* 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}`);
}

使用

参数说明

// merges：用来合并单元格，值为数组
// const merges = ['A1:A2', 'C1:D1', 'C2:D2']
// excel 单元格是按所在的行列位置来命名,行从左到右[A-X],列从上到下[1-100+]。我们如果说第一行（1）第二列（B），则成为B1
// A1:A3 则表示从第一行第一列合并至第三行第一列
// 如果不明白，可以对照下excel中的行列就很明确了

// header 表头
// 如果只有单级表头，header 就是表头的字段名
// 如果有多级表头，表头为最下面那一层的名称
// 如果一个表格占不止一列，一般是第一列写表头字段名，第二列为''。对应的数据也需要加上''。记得合并单元格。
// const header = ['日期'， ‘’， ‘姓名’]
// const data = ['date', '', 'name']

// multiHeader
// const multiHeader = [], 一个值表示一行的配置，其值也是数组
// 多级表头的规则与表头是一样的。
// 例：const multiHeader = [['日期'，‘姓名']， []]
// 因为数据占的列数不同，这里需要注意

// data： 数据
// data 需要如下例子方法，处理下参数

导出单级表头表格

点击导出结果，如下图所示：

代码如下：

模板语法：

<template>
  <div>
    <el-button 
    	@click="exportTable" 
    	type="primary"
    >导出表格</el-button>
    <el-table 
    	:data="tableData" 
    	style="width: 100%"
    >
      <el-table-column 
     		prop="date" 
     		label="日期"
        width="180"
     	>
      </el-table-column>
      <el-table-column 
      	prop="name" 
      	label="姓名" 
      	width="180"
      >
      </el-table-column>
      <el-table-column 
      	prop="address" 
      	label="地址"
      >
      </el-table-column>
    </el-table>
  </div>
</template>

js代码：

<script>
export default {
	data() {
    return {
      tableData: [{
        date: '2016-05-02',
        name: '王小虎',
        address: '上海市普陀区金沙江路 1518 弄'
      }, {
        date: '2016-05-04',
        name: '王小虎',
        address: '上海市普陀区金沙江路 1517 弄'
      }, {
        date: '2016-05-01',
        name: '王小虎',
        address: '上海市普陀区金沙江路 1519 弄'
      }, {
        date: '2016-05-03',
        name: '王小虎',
        address: '上海市普陀区金沙江路 1516 弄'
      }]
    }
  },

  methods: {
    exportTable(){
      // 表头按顺序配置
      const tHeader = ['日期', '姓名', '地址']
      // 将数据按导出格式处理
      const filterVal = ['date', 'name', 'address']
      const list = this.tableData
      const data = this.formatJson(filterVal, list)

      import('@/vendor/Export2Excel')
      .then(excel => {
        excel.export_json_to_excel({
          header: tHeader, //表头 必填
          data, //具体数据 必填
          filename: 'excel-list', //非必填
          autoWidth: true, //非必填
          bookType: 'xlsx' //非必填
        })
      })
    },

    formatJson(filterVal, jsonData) {
      return jsonData.map(v => filterVal.map(j => {
        if (j === 'timestamp') {
          return parseTime(v[j])
        } else {
          return v[j]
        }
      }))
    },
  },
}
</script>

导出多级表头数据

代码如下所示：

模板语法：

<template>
  <div>
    <el-button 
    	type="primary" 
    	@click="exportTable"
    >
    	导出表格
    </el-button>
    <el-table
      :data="tableData"
      style="width: 100%">
      <el-table-column
        prop="date"
        label="日期"
        width="150">
      </el-table-column>
      <el-table-column label="配送信息">
        <el-table-column
          prop="name"
          label="姓名"
          width="120">
        </el-table-column>
        <el-table-column label="地址">
          <el-table-column
            prop="province"
            label="省份"
            width="120">
          </el-table-column>
          <el-table-column
            prop="city"
            label="市区"
            width="120">
          </el-table-column>
          <el-table-column
            prop="address"
            label="地址"
            width="300">
          </el-table-column>
          <el-table-column
            prop="zip"
            label="邮编"
            width="120">
          </el-table-column>
        </el-table-column>
      </el-table-column>
    </el-table>
  </div>
</template>

js部分：

<script>
export default {
  data() {
    return {
      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
      }, {
        date: '2016-05-04',
        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: '2016-05-01',
        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: '2016-05-08',
        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
      }]
    };
  },
  methods: {
    exportTable(){
      import('@/vendor/Export2Excel')
      .then(excel => {
        // 因为配送信息下面有5列，所以第一行表头我们要有6列,并且要将行数合并
        // 第二行日期这个是一致的，所以要配置'',以此类推
        // 数据几位当前要显示的数据
        const multiHeader = [
          ['日期', '配送信息', '', '', '', ''],
          ['', '姓名', '地址', '','', '']
        ]
        const tHeader = ['', '', '省份', '市区', '地址', '邮编']
        const filterVal = ['date', 'name', 'province', 'city', 'address', 'zip']
        const list = this.tableData
        const data = this.formatJson(filterVal, list)
        // 1.合并日期 2.合并姓名 3.合并配送信息 4.合并地址
        const merges = ['A1:A3', 'B2:B3', 'B1:F1', 'C2:F2']
        excel.export_json_to_excel({
          multiHeader,
          header: tHeader, //表头 必填
          data, //具体数据 必填
          filename: '测试报表', //非必填
          autoWidth: true, //非必填
          bookType: 'xlsx', //非必填
          merges,

        })
      })
    },

    formatJson(filterVal, jsonData) {
      return jsonData.map(v => filterVal.map(j => {
        if (j === 'timestamp') {
          return parseTime(v[j])
        } else {
          return v[j]
        }
      }))
    },
  },
};
</script>