table2excel/src/index.js

convert and download html tables to a xlsx-file that can be opened in Microsoft Excel

import 'xlsx-style/dist/xlsx.core.min';

import { saveAs } from 'filesaver.js';

import tableToData from './helpers/table-to-data';
import dataToWorksheet from './helpers/data-to-worksheet';

import listHandler from './types/list';
import numberHandler from './types/number';
import dateHandler from './types/date';
import inputHandler from './types/input';
import booleanHandler from './types/boolean';

/**
 * @param {string} defaultFileName - The file name if download
 * doesn't provide a name. Default: 'file'.
 * @ param {string} tableNameDataAttribute - The identifier of
 * the name of the table as a data-attribute. Default: 'excel-name'
 * results to `<table data-excel-name="Another table">...</table>`.
 */
const defaultOptions = {
  defaultFileName: 'file',
  tableNameDataAttribute: 'excel-name',
};

/**
 * The default type handlers: lists, numbers, dates, input fields and booleans.
 */
const typeHandlers = [
  listHandler,
  inputHandler,
  numberHandler,
  dateHandler,
  booleanHandler,
];

/**
 * Creates a `Table2Excel` object to export HTMLTableElements
 * to a xlsx-file via its function `export`.
 */
export default class Table2Excel {
  /**
   * @param {object} options - Overrides the default options.
   */
  constructor(options = {}) {
    Object.assign(this, defaultOptions, options);
  }

  /**
   * Exports HTMLTableElements to a xlsx-file.
   *
   * @param {NodeList} tables - The tables to export.
   * @param {string} fileName - The file name.
   */
  export(tables, fileName = this.defaultFileName) {
    this.download(this.getWorkbook(tables), fileName);
  }

  /**
   * Get the XLSX-Workbook object of an array of tables.
   *
   * @param {NodeList} tables - The tables.
   * @returns {object} - The XLSX-Workbook object of the tables.
   */
  getWorkbook(tables) {
    return Array.from(tables.length ? tables : [tables])
      .reduce((workbook, table, index) => {
        const dataName = table.getAttribute(`data-${this.tableNameDataAttribute}`);
        const name = dataName || (index + 1).toString();

        workbook.SheetNames.push(name);
        workbook.Sheets[name] = this.getWorksheet(table);

        return workbook;
      }, { SheetNames: [], Sheets: {} });
  }

  /**
   * Get the XLSX-Worksheet object of a table.
   *
   * @param {HTMLTableElement} table - The table.
   * @returns {object} - The XLSX-Worksheet object of the table.
   */
  getWorksheet(table) {
    if (!table || table.tagName !== 'TABLE') {
      throw new Error('Element must be a table');
    }

    return dataToWorksheet(tableToData(table), typeHandlers);
  }

  /**
   * Exports a XLSX-Workbook object to a xlsx-file.
   *
   * @param {object} workbook - The XLSX-Workbook.
   * @param {string} fileName - The file name.
   */
  download(workbook, fileName = this.defaultFileName) {
    function convert(data) {
      const buffer = new ArrayBuffer(data.length);
      const view = new Uint8Array(buffer);
      for (let i = 0; i <= data.length; i++) {
        view[i] = data.charCodeAt(i) & 0xFF;
      }
      return buffer;
    }

    const data = window.XLSX.write(workbook, {
      bookType: 'xlsx',
      type: 'binary',
    });

    const blob = new Blob([convert(data)], { type: 'application/octet-stream' });
    saveAs(blob, `${fileName}.xlsx`);
  }
}

// add global reference to `window` if defined
if (window) window.Table2Excel = Table2Excel;

/**
 * Adds the type handler to the beginning of the list of type handlers.
 * This way it can override general solutions provided by the default handlers
 * with more specific ones.
 *
 * @param {function} typeHandler - Type handler that generates a cell
 * object for a specific cell that fulfills specific criteria.
 * *
 * * @param {HTMLTableCellElement} cell - The cell that should be parsed to a cell object.
 * * @param {string} text - The text of the cell.
 * *
 * * @returns {object} - Cell object (see: https://github.com/SheetJS/js-xlsx#cell-object)
 * * or `null` iff the cell doesn't fulfill the criteria of the type handler.
 */
Table2Excel.extend = function extendCellTypes(typeHandler) {
  typeHandlers.unshift(typeHandler);
};