# SheetJS — Read and Write Spreadsheets from JavaScript

> A comprehensive JavaScript library for parsing and writing Excel, CSV, and other spreadsheet formats in the browser and Node.js.

## Install

Save as a script file and run:

# SheetJS — Read and Write Spreadsheets from JavaScript

## Quick Use
```bash
npm install xlsx
```
```js
const XLSX = require('xlsx');
const workbook = XLSX.readFile('data.xlsx');
const sheet = workbook.Sheets[workbook.SheetNames[0]];
const json = XLSX.utils.sheet_to_json(sheet);
console.log(json);
```

## Introduction
SheetJS (also published as the `xlsx` npm package) provides a pure-JavaScript engine for reading, editing, and writing spreadsheet data. It handles dozens of file formats—XLS, XLSX, CSV, ODS, and more—without native dependencies, making it suitable for both server-side Node.js scripts and in-browser applications.

## What SheetJS Does
- Parses Excel files (XLS, XLSX, XLSB) into a uniform workbook object model
- Writes workbooks back to XLSX, CSV, HTML, JSON, and other output formats
- Runs in the browser with no server round-trips, enabling client-side export
- Converts between row-major arrays, JSON arrays, and HTML tables
- Handles multi-sheet workbooks, merged cells, number formats, and date parsing

## Architecture Overview
SheetJS exposes a workbook/sheet data model. File bytes are fed to a format-specific parser that produces a workbook object containing named sheets. Each sheet is a sparse two-dimensional map of cell objects keyed by A1-style references. Utility functions convert between this internal representation and developer-friendly structures like arrays of objects. Writers serialize the workbook back into the target binary or text format.

## Setup & Configuration
- Install from npm: `npm install xlsx` or load via CDN for browser use
- Import with `require('xlsx')` (CJS) or `import * as XLSX from 'xlsx'` (ESM)
- No native add-ons or external binaries required
- Use the streaming API (`XLSX.stream`) for large files that exceed memory limits
- Configure date handling with `cellDates: true` in the parsing options

## Key Features
- Supports 20+ spreadsheet formats including legacy XLS and modern XLSB
- Zero native dependencies—runs identically in Node.js, Deno, and browsers
- Streaming reader and writer for processing large files efficiently
- Rich cell metadata including types, styles, formulas, and comments
- Active maintenance with frequent releases since 2012

## Comparison with Similar Tools
- **ExcelJS** — provides deeper style and image support but only handles XLSX; SheetJS covers far more formats
- **Papa Parse** — CSV-only parser; SheetJS handles CSV plus binary Excel and ODS
- **openpyxl (Python)** — Python equivalent for XLSX; SheetJS brings the same capability to JavaScript
- **Tabulator** — focuses on UI table rendering; SheetJS focuses on file I/O

## FAQ
**Q: Can SheetJS run in the browser without a server?**
A: Yes. It parses files entirely in the browser using the File API or drag-and-drop input.

**Q: Does SheetJS support writing styled XLSX files?**
A: The community edition handles data and basic number formats. The Pro edition adds full styling, images, and pivot tables.

**Q: How does SheetJS handle large files?**
A: Use the streaming API to process rows incrementally rather than loading the entire workbook into memory.

**Q: Is SheetJS free and open source?**
A: The core library is released under the Apache-2.0 license. An optional Pro tier adds advanced features.

## Sources
- https://github.com/SheetJS/sheetjs
- https://docs.sheetjs.com/

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Source: https://tokrepo.com/en/workflows/asset-2c6f3366
Author: Script Depot