https://github.com/pyramation/etag-stream

A Transform stream that calculates Etag/S3 MD5 sum. Uses the same algorithm as S3.
https://github.com/pyramation/etag-stream

es6 etag javascript node-module npm s3 streams

Last synced: about 1 month ago
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A Transform stream that calculates Etag/S3 MD5 sum. Uses the same algorithm as S3.

• Host: GitHub
• URL: https://github.com/pyramation/etag-stream
• Owner: pyramation
• License: mit
• Created: 2018-10-14T03:36:30.000Z (over 7 years ago)
• Default Branch: master
• Last Pushed: 2020-10-01T00:25:06.000Z (over 5 years ago)
• Last Synced: 2025-03-13T02:03:51.469Z (about 1 year ago)
• Topics: es6, etag, javascript, node-module, npm, s3, streams
• Language: JavaScript
• Size: 6.72 MB
• Stars: 0
• Watchers: 1
• Forks: 1
• Open Issues: 1
• Metadata Files:
  • Readme: readme.md
  • License: LICENSE

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README

          
# ETag Stream ![Build Status](https://travis-ci.org/pyramation/etag-stream.svg?branch=master)

A Transform stream that calculates Etag/S3 MD5 sum. Uses the same algorithm that S3 uses to calculate the `ETag`.

This is especially useful for verifying large files uploaded using multipart S3 API, enabling use of `createReadStream` to keep memory usage low.

## Installation

```sh

npm install etag-stream

```

## Usage

```js

const ETagStream = require('etag-stream');

const stream = new ETagStream();

let result = null;

stream

  .on('error', e => {

    reject(e);

  })

  .on('etag', data => {

    result = data.toString();

  })

  .on('data', data => {

    // data passes through if you need to do more!

  })

  .on('finish', () => {

    resolve(result);

  });

createReadStream(local).pipe(stream);

```

ETags compatible with s3, thanks to the author of [this post](https://stackoverflow.com/questions/12186993/what-is-the-algorithm-to-compute-the-amazon-s3-etag-for-a-file-larger-than-5gb#answer-19896823) for the breakdown of the algorithm.