JS function: convert objects in an array or object to rows in a CSV file

to-csv.js

/*
	usage:

	var csvString = toCSV({
		key1: { col1: 5, col2: 'hi' },
		key2: { col1: 7, col2: 'hello' }
	}, {
		// default config:
		includeKeys: true,
		delimiter: ',',
		filterAndMap: {
			// propToExclude: false,
			// propToCustomize: function(val) { return customVal; }
		}
	});

	var csvString = toCSV([
		{ col1: 5, col2: 'hi' },
		{ col1: 7, col2: 'hello' }
	]);
	
*/

function toCSV(rows, config) {
	var has = Function.prototype.call.bind(Object.prototype.hasOwnProperty);
	var indexByColumnHeading = {};
	var columnHeadings = [];
	var csv = '';
	config = config || {};
	var delimiter = config.delimiter === undefined ? ',' : config.delimiter;
	var includeKeys = config.includeKeys === undefined ? true : config.includeKeys;
	var filterAndMap = config.filterAndMap || {};
	
	// turn each object into a row
	for (var key in rows) {
		// skip properties of prototype
		if (!has(rows, key)) continue;
		
		// add row
		var rowObject = rows[key];
		var cells = [];
		if (includeKeys) {
			columnHeadings[0] = 'key';
			cells[0] = key;
		}
		
		// turn each property into a cell
		for (var columnHeading in rowObject) {
			// skip excluded properties and those of prototype
			if (filterAndMap[columnHeading] === false || !has(rowObject, columnHeading)) continue;

			// store the column heading
			if (indexByColumnHeading[columnHeading] === undefined) {
				columnHeadings.push(columnHeading);
				indexByColumnHeading[columnHeading] = columnHeadings.length - 1;
			}

			// add cell
			var value = typeof filterAndMap[columnHeading] === 'function' ?
				filterAndMap[columnHeading](rowObject[columnHeading]) :
				rowObject[columnHeading];
			value = String.prototype.split.call(value, '"').join('""');
			if (String.prototype.indexOf.call(value, ',') >= 0) value = '"' + value + '"';
			cells[indexByColumnHeading[columnHeading]] = value;
		}
		csv += '\n' + cells.join(delimiter);
	}
	return columnHeadings.join(delimiter) + csv;
}