but-csv

but-csv

479 byte (minified) CSV parser and builder. Smaller when compressed. Built in ESM only.

Doesn't care about headers, keyed rows, anything but strings. Just supports the CSV spec including multi-line and quoted strings.

Usage

Install via you favourite package manager and import but-csv. Has zero dependencies (obviously).

$ npm install but-csv

Parse

Parses a CSV into an array of array of strings. Supports varied line lengths. Does not convert to numbers or any other formats.

import { parse } from 'but-csv';

const out = parse('foo,bar,zing\n1,2,3\n4,5');
// out will be [['foo', 'bar', 'zing'], ['1', '2', '3'], ['4','5']]

Only supports passing a string (not a Buffer or friends). Node's operations on string are so much faster than on raw bytes (10x improvement). If you're parsing a file, do this:

const f = fs.readFileSync('source.csv', 'utf-8');
const out = parse(f);

Iterator

Like parse, but you get each row at a time so you can stop early.

import { iter } from 'but-csv';

for (const row of iter('foo,bar,zing\n1,2,3\n4,5')) {
  // row will be an array of:
  // 1. ['foo', 'bar', 'zing'],
  // 2. ['1', '2', '3']
  // 3. ['4','5']
}

Build

You can pass any value and it will be stringified before render, useful for numbers. This is unlike the parser above, which only returns strings.

import { build } from 'but-csv';

const out = build([
  ['hello', 'there"\n'],
  [1, 2],
]);

// out will be:
// hello,"there""
// "
// 1,2

Advanced

Be sure to turn on your bundler's tree-shaking ability (good practice in general), but especially if you're only parsing or building, because the code is separate. Parsing is about 75% of the code, and building 25%.

Speed

It's very fast, but doesn't support streaming. To parse multiple copies of 1.csv from here, parsing all at once:

but-csv: 732.908ms
papaparse: 1.337s (1.8x)
csv-parser: 2.283s (3.1x)