Csvster NPM | npm.io

Csvster

Quick and simple CSV reader and writer.

Usage

Most use cases are accomodated by the static class methods, but the class can be instantiated for other cases.

API

import Csvster from 'csvster';

// static methods (easiest)

// read a buffer or string that is the entirety of the dataset
// onRow is optional
Csvster.read(bufferOrString, options, onRow);

// return a stream object (writable or transform)
// onRow is optional
Csvster.reader(options, onRow);

// resolves after the stream has been read
// onRow is called for each row read
// options are optional
await Csvster.readStream(stream, onRow, options);

// write rows (array of arrays or objects)
// onRow is optional
Csvster.write(arraysOrObjects, options, onRow);

// return a stream object (writable or transform)
// onRow is optional
Csvster.writer(options, onRow);

// resolves after the stream has been written
// pushRow is called once and returns a function that takes row data (array or object)
// options are optional
await Csvster.writeStream(stream, pushRow, options);

// class methods (for custom implementations and not normally needed)

// read a buffer or string that is the entirety of the dataset
// optionally each row is passed to onRow
(new Csvster(options)).readAll(bufferOrString, onRow);

// read a buffer or string that is a chunk of the dataset
// optionally each completed row is passed to onRow
(new Csvster(options)).readPartial(bufferOrString, onRow);

// write the header to a string
// optionally provide a header to set it on the object
(new Csvster(options)).writeHeader(header);

// write a row of array or object data
(new Csvster(options)).writeRow(arrayOrObject);

// write rows of array of arrays or objects
// optionally provide a header (or true flag to use the header on the object) to write a header row
// optionally passes each row to onRow
(new Csvster(options)).writeRows(arraysOrObjects, headerOrFlag, onRow);

Options

Option	Default	Description
header	`false`	Array of header names or a true flag indicating to use the first row as a header.
map	`false`	Map rows to header names.
cast	`false`	Cast values to their most likely json types (`bool`, `number`, or `string`).
skipEmptyLines	`false`	Skip empty lines (lines with no columns or all empty columns).
keepBom	`false`	Keep a file `BOM` (byte order mark) in returned rows (if found in file).
delimiter	`,`	CSV column delimiter, set to `null` to autodetect.
lineDelimeter	`\r\n`	CSV line column delimiter (only used for write mode).

Examples

import fs from 'fs';
import Csvster from 'csvster';

// read a file
function readFromFile() {
	let data = fs.readFileSync('test.csv', 'utf8');
	let rows = Csvster.read(data, { header: true });
}

// read a file stream
async function fileStreamExample() {
	return new Promise((res, rej) => {

		let rows = [];

		let stream = fs.createReadStream('test.csv', 'utf8');
		let pipe = stream.pipe(Csvster.reader());

		stream.on('error', rej);
		pipe.on('error', rej);

		pipe.on('data', (row) => rows.push(row));
		pipe.on('done', () => res(rows));
	});
}

// read a file stream (callback)
async function fileStreamExample() {
	return new Promise((res) => {

		let rows = [];

		let stream = fs.createReadStream('filename.csv', 'utf8');
		stream.pipe(Csvster.reader(undefined, (row) => {
			if (row == null) {
				res(rows);
			} else {
				rows.push(row);
			}
		}));
	});
}

// write array or arrays
function writeArrays() {
	let data = [['a', 'b', 'c'], [1, 2, 3], [4, 5, 6]];
	fs.writeFileSync('filename.csv', Csvster.write(data));
}

// write array of objects
function writeObjects() {
	let data = [{ a: 1, b: 2, c: 3 }, { a : 4, b: 5, c: 6 }];
	fs.writeFileSync('filename.csv', Csvster.write(data));
}

// write a stream
async function writeStream() {
	return new Promise((res, rej) => {

		let stream = fs.createWriteStream('filename.csv', 'utf8');
		let data = [['a', 'b', 'c'], [1, 2, 3], [4, 5, 6]];

		let writer = Csvster.writer();
		let pipe = writer.pipe(stream);

		writer.on('error', rej);
		stream.on('error', rej);

		for (let row of data) {
			writer.push(row);
		}

		writer.end(() => res());
	});
}

Benchmarks

Reading a stream of semi-randomized data set of 10 cols x 1M rows.
All packages initialized with their respective defaults.
Row data contains strings, escaped strings, numbers, and booleans.
Benchmark code can be found in test/tests/benchmarks.js.