xlsx to json parsing

xlsx.ts

import * as _ from 'lodash';
import * as csv from 'fast-csv';
import * as ExcelJS from 'exceljs';

export interface Column {
  key: string;
  header: string;
}

export async function xlsxToJSON<T>(filePath: string, columns: Partial<Column>[]): Promise<T[]> {
  const workbook = new ExcelJS.Workbook();
  await workbook.xlsx.readFile(filePath);
  const buffer = await workbook.csv.writeBuffer();

  const items: T[] = [];
  return new Promise((resolve, reject) =>
    csv
      .parseString(buffer.toString(), { headers: true })
      .transform((data) => {
        return Object.keys(data).reduce((item, header) => {
          const column = columns.find((column) => column.header === header);
          if (column && column.key) {
            item[column.key] = data[header];
          }
          return item;
        }, {});
      })
      .on('error', (error) => reject(error))
      .on('data', (row) => items.push(row))
      .on('end', () => resolve(items.filter((item) => !_.isEmpty(item)))),
  );
}