element-ui导出excel

要使用element-ui导出excel，需要先安装依赖包：`npm install -S file-saver xlsx`，然后在代码中引入相关模块：

import { export_json_to_excel } from '@/excel/Export2Excel'
import XLSX from 'xlsx'
import FileSaver from 'file-saver'

其中，`export_json_to_excel`是一个自定义的函数，用于将JSON数据导出为Excel文件。具体实现可以参考以下代码：

export function export_json_to_excel(th, jsonData, defaultTitle) {
  /* original data */
  const data = jsonData
  data.unshift(th)
  const ws_name = 'SheetJS'
  const wb = new Workbook()
  const ws = sheet_from_array_of_arrays(data)
  /* add worksheet to workbook */
  wb.SheetNames.push(ws_name)
  wb.Sheets[ws_name] = ws
  const wbout = XLSX.write(wb, { bookType: 'xlsx', bookSST: false, type: 'binary' })
  const title = defaultTitle || '列表'
  saveAs(new Blob([s2ab(wbout)], { type: 'application/octet-stream' }), `${title}.xlsx`)
}

function sheet_from_array_of_arrays(data) {
  const ws = {}
  const range = { s: { c: 10000000, r: 10000000 }, e: { c: 0, r: 0 } }
  for (let R = 0; R !== data.length; ++R) {
    for (let 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
      const cell = { v: data[R][C] }
      if (cell.v == null) continue
      const 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 datenum(v, date1904) {
  if (date1904) v += 1462
  const epoch = Date.parse(v)
  const excelEpoch = Date.parse('1900-01-01T00:00:00')
  return (epoch - excelEpoch) / (24 * 60 * 60 * 1000)
}

function s2ab(s) {
  const buf = new ArrayBuffer(s.length)
  const view = new Uint8Array(buf)
  for (let i = 0; i !== s.length; ++i) view[i] = s.charCodeAt(i) & 0xff
  return buf
}

使用时，只需要调用`export_json_to_excel`函数即可：

exportExcel() {
  require.ensure([], () => {
    const { export_json_to_excel } = require('@/excel/Export2Excel')
    const tHeader = ['姓名', '年龄', '性别', '爱好', '地址']
    const filterVal = ['name', 'age', 'sex', 'interest', 'address']
    const list = this.tableData
    const data = this.formatJson(filterVal, list)
    export_json_to_excel(tHeader, data, '列表')
  })
}

其中，`tHeader`是表头，`filterVal`是要导出的字段，`list`是要导出的数据。