CSV generator example

objToCsv.js

'use strict';

let objToCsv = (function() {
  let defaultOptions = {
    showLabel: true,
    lineBreak: '\r\n',
    separator: ','
  };

  // escape quotes
  let naiveFixString = str => typeof str === 'string' ? str.replace(/"/g, '\"') : '';

  // escape quotes and then quote
  let quoteString = str => '"' + naiveFixString(str) + '"';

  /**
    * take an array of row objects, output CSV string
    * @param {Object[]} rowArray - list of row objects
    * @param {string} title - the title which is displayed in the first lines of the output (default to '')
    * @param {Object} options - options object with sane defaults (see below)
    * @param {boolean} [options.showLabel=true] - whether to include column labels in the output
    * @param {string} [options.lineBreak='\r\n'] - string to separate lines
    * @returns {string} single (multiline) string CSV output
    */
  function objToCsv(rowArray, title, options) {
    let opts = Object.assign({}, defaultOptions, options);

    if (!rowArray || !rowArray.length) return {message: 'invalid row list', data:rowArray};
    if (!rowArray[0].hasOwnProperty('Cells')) return {message: 'no Cells object', data:rowArray[0]};

    const colNames = 
      Object.keys(rowArray.reduce( (accum, cur) => {
        Object.keys(cur['Cells']).forEach( key => accum[key] = true );
        return accum;
      }, {})).sort()
    
    return (title ? opts.lineBreak + title + opts.lineBreak + opts.lineBreak: '') +   
      (opts.showLabel 
        ? colNames.map(quoteString).join(opts.separator) + opts.lineBreak
        : ''
      ) +
      rowArray.map( row => {
        return colNames.map( colName => quoteString(row.Cells[colName]) || '' );
      }).join(opts.lineBreak);
  } 

  return objToCsv;
}());