Vnosko Lite by PN Scripts

Read CSV, TSV and XLSX files in the browser or in Node with no dependencies, find the header row, match the columns to your fields by name and aliases, and get typed, checked rows: numbers as numbers, dates as YYYY-MM-DD, booleans, choices, e-mails, URLs, phone numbers, required and unique values. MIT.

npm install @pnscripts/vnosko-lite

import { readFile, findHeaderRow, autoMap, checkRows } from '@pnscripts/vnosko-lite';

const fields = [
  { key: 'name', label: 'Name', required: true, aliases: ['full name', 'customer'] },
  { key: 'email', label: 'Email', type: 'email', required: true, unique: true },
  { key: 'plan', label: 'Plan', type: 'enum', options: ['free', { value: 'pro', label: 'Pro', aliases: ['premium'] }] },
  { key: 'seats', label: 'Seats', type: 'integer', min: 1, max: 500 },
  { key: 'signedUp', label: 'Signed up', type: 'date' },
];

const file = await readFile(input.files[0]);          // a File/Blob (browser) or { arrayBuffer } (Node)
const rows = file.sheets[0].rows;                     // string[][]
const header = findHeaderRow(rows, fields);           // skips title lines above the headings
const mapping = autoMap(rows[header], fields);        // { name: 0, email: 2, ... }
const checked = checkRows(rows.slice(header + 1), mapping, fields);
// [{ index, values: { name, email, plan, seats, signedUp }, raw, errors: { email: 'email' } }, ...]

What it reads

• CSV and TSV in UTF-8 (with or without BOM), UTF-16 or Windows-1252; , ; tab or | found automatically; quotes, doubled quotes and line breaks inside quotes.
• XLSX with several sheets, shared strings, dates (Excel serial numbers and date formats) and booleans, unzipped with the browser's own DecompressionStream (Node 18+ too). Old .xls files are refused with a clear error.
• Numbers written 1 299,90, 1,299.90 or 1.299,90; dates day-first (default) or month-first; yes/no in several languages.

Also included

• templateCsv(fields): a CSV your users can fill in, with your labels and one example row that imports without errors.
• message() / errorText(): error texts in English and Bulgarian, or your own.
• TypeScript types; ESM and CommonJS builds.

Tested

• 8 tests with Node's runner (npm test), including real XLSX and Windows-1252 files.
• tools/buyer_check.sh: npm pack, a fresh project installs the tarball, ESM and CommonJS read the files. Node 22. Browsers: the same code runs in the full edition's Chrome demo check.

Vnosko (full edition)

Vnosko adds the React import wizard on top of this engine: drag and drop or paste from a spreadsheet, column matching your users can correct, errors shown per cell and fixed by typing, remove or skip bad rows, a template download and English/Bulgarian texts: https://pnscripts.com/marketplace/react-vnosko. Lite is complete for reading and checking and never asks for payment.

Licence

MIT, see LICENSE. Copyright (c) 2026 ПН СКРИПТС ЕООД (PN Scripts).