@openmeteo/file-reader/README.md

JavaScript reader for the om file format using WebAssembly

# Open-Meteo File-Reader

JavaScript/TypeScript bindings for the [Open-Meteo File Format](https://github.com/open-meteo/om-file-format/)!

## Overview

This library provides JavaScript/TypeScript bindings to the OmFileFormat C library through WebAssembly. It enables efficient reading of OmFile data in web browsers and Node.js environments.

## Features

- Read OmFile format (scientific data format optimized for meteorological data)
- High-performance data access through WebAssembly
- Multiple backends for different data sources:
  - File backend for local files
  - Memory/HTTP backend for remote files
  - S3 backend for files in AWS S3
- Browser and Node.js compatibility
- TypeScript type definitions included

## Installation

```bash
npm install @openmeteo/file-reader
```

## Usage

Usage depends on the backend you want to use to access the data and the environment you are in (Node, Browser). Expect this to be improved in the future!

### Node.js: Reading from a Local File

```typescript
import { OmFileReader, FileBackendNode } from '@openmeteo/file-reader';

const backend = new FileBackendNode('/path/to/your/file.om');
const reader = await OmFileReader.create(backend);

const data = await reader.readVariable('temperature');
console.log(data);
```

### Browser: Reading from a File Input

```typescript
import { OmFileReader, FileBackend } from '@openmeteo/file-reader';

// Assume you have a <input type="file" id="fileInput" />
const fileInput = document.getElementById('fileInput');
fileInput.addEventListener('change', async (event) => {
  const file = event.target.files[0];
  const backend = new FileBackend(file);
  const reader = await OmFileReader.create(backend);

  const data = await reader.readVariable('temperature');
  console.log(data);
});
```

### In-Memory Data

```typescript
const buffer = new Uint8Array([...]); // Your OmFile data
const backend = new FileBackend(buffer);
const reader = await OmFileReader.create(backend);
```

### Remote HTTP File

```typescript
import { MemoryHttpBackend, OmFileReader } from '@openmeteo/file-reader';

const backend = new MemoryHttpBackend({ url: 'https://example.com/data.om' });
const reader = await OmFileReader.create(backend);
```

## License

This code depends on [TurboPFor](https://github.com/powturbo/TurboPFor-Integer-Compression) and [open-meteo](https://github.com/open-meteo/open-meteo) code; their license restrictions apply.