---
title: "Process Spreadsheet Data with SheetJS"
date: 2022-11-21T17:19:49.000Z
author: Z.SHINCHVEN
tags: [Node.js, SheetJS, XLSX]
canonical: https://atlassc.net/2022/11/21/process-spreadsheet-data-with-sheetjs
---
[SheetJS](https://www.npmjs.com/xlsx), aka the `xlsx` package for JavaScript, is probably the most commonly used sheet processing library. 

Compared to [ExcelJS](https://www.npmjs.com/exceljs), it supports more data formats like the old `xls` and can be used across multiple platforms.

## Access Spreadsheet Data

To access spreadsheet data with SheetJS, you need to first read the sheet data from byte[] or file, then convert it to JSON format using the provided utils [XLSX.utils.sheet_to_json](https://docs.sheetjs.com/docs/solutions/output#api-1);

Here's an example of how I do it:

```ts
import XLSX from 'xlsx';

const filepath = "path/to/file.xlsx";
await fs.access(filepath, fs.constants.R_OK);

// Read workbook from file
const workbook = XLSX.readFile(filepath);
// Access sheet in a workbook
const [sheetName] = workbook.SheetNames;
const sheet = workbook.Sheets[sheetName];
// Convert sheet data to json, which is an array of arrays.
const rows = XLSX.utils.sheet_to_json(sheet, {header: 1});
const customers: Array<Partial<CustomerModel>> = [];
// Access data from each row
for (let i = 0; i < rows.length; i++) {
  if (i > 0) { // Skip sheet header row
    // Row data to object.
    const row = rows[i] as any[];
    const customer = {
      code: row[0],
      name: row[1],
      gender: row[2],
    };
    customers.push(customer);
  }
}
console.log(customers);
```