Registry / http-networking / event-stream-parser

event-stream-parser

library1.0.2jsnpmunverified

The `event-stream-parser` package provides a lightweight, zero-dependency implementation for parsing Server-Sent Events (SSE) streams, strictly adhering to the HTML Living Standard specification. Designed to leverage the Web Streams API, it offers full compatibility with modern web browsers and Node.js environments (requiring Node.js >=18.0.0). The current stable version is `1.0.2`, with a release cadence that has been fairly rapid since its initial v1.0.0 release in early 2024. Its key differentiators include its minimalistic design, native Web Streams integration for efficient processing, and comprehensive TypeScript support, making it an ideal choice for applications requiring robust and standards-compliant SSE consumption without external bloat.

http-networking serialization

npm install event-stream-parser

github ↗package ↗

INSTALL

IMPORT

SIG · EVENT-STREAM-PARSE

event-stream-parser

http-networkingjavascriptv1.0.2

Install

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Import

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Disk

—

Pass rate

0/ 6

Env Coverage0 / 6

glibc

18–22

musl

18–22

Install & Compatibility

Where this runs

tested against v? · npm install

Install × environment matrix

Each cell = how many times install + import succeeded across repeated harness runs. Partial = flaky.
glibc = Debian/Ubuntu slim · musl = Alpine Linux

musl

node 18–226 runs

build_error

glibc

node 18–226 runs

build_error

Code

Verified usage

Verified import paths — ran on the pinned version, not inferred.

parse

✓ import { parse } from 'event-stream-parser';

✗ import parse from 'event-stream-parser';

The `parse` function is a named export. Default imports will not work. This package is ESM-only.

parse

✓ import { parse } from 'event-stream-parser/v1';

✗ const { parse } = require('event-stream-parser');

Explicitly importing from '/v1' is supported. CommonJS `require()` syntax is not supported as the package is ESM-only.

MessageEvent (type)

✓ import type { MessageEvent } from 'event-stream-parser';

For type-checking in TypeScript, import the `MessageEvent` type if you need to explicitly type stream events.

Demonstrates how to fetch a Server-Sent Events stream using `fetch`, parse it with `event-stream-parser`, and consume the resulting `MessageEvent` objects via a `WritableStream`.

import { parse } from 'event-stream-parser'; async function fetchAndParseEvents() { const sseApiUrl = process.env.SSE_API_URL ?? 'https://demo.vercel.events/api/kitchensink'; // Example SSE endpoint try { const response = await fetch(sseApiUrl, { headers: { 'Accept': 'text/event-stream', 'Cache-Control': 'no-cache', 'Connection': 'keep-alive' }, }); if (!response.ok) { throw new Error(`HTTP error! Status: ${response.status}`); } if (!response.body) { throw new Error('Response body is null; server might not be sending a stream.'); } console.log(`Connected to SSE stream at ${sseApiUrl}`); const eventStream = await parse(response.body); await eventStream.pipeTo( new WritableStream<MessageEvent>({ write(event) { console.log('\n--- Event Received ---'); console.log(`Type: ${event.type || '[default]'}`); console.log(`Data: ${event.data}`); if (event.lastEventId) { console.log(`Last Event ID: ${event.lastEventId}`); } }, close() { console.log('\n--- Event Stream Closed ---'); }, abort(reason) { console.error('\n--- Event Stream Aborted ---', reason); } }) ); } catch (error) { console.error('Failed to fetch or process event stream:', error); } } fetchAndParseEvents();

Debug

Known issues

gotchaThe `parse` function returns a `Promise<ReadableStream<MessageEvent>>`, not directly a `ReadableStream`. Ensure you `await` the result of `parse` before attempting to pipe or read from the event stream.

fix

Use `const eventStream = await parse(response.body);` instead of `const eventStream = parse(response.body);`

affects: >=1.0.0

gotchaThis package requires Node.js version 18.0.0 or higher due to its reliance on modern Web Streams API features and ESM module system. Running on older Node.js versions will result in compatibility errors.

fix

Upgrade your Node.js environment to version 18 or newer (e.g., `nvm install 18 && nvm use 18`).

affects: >=1.0.0

gotchaWhen using `fetch` to consume an SSE stream, it is crucial to set the `Accept: 'text/event-stream'` header. Additionally, `Cache-Control: 'no-cache'` and `Connection: 'keep-alive'` are often necessary for proper streaming behavior, although not strictly required by the parser itself.

fix

Ensure your `fetch` request includes `{ headers: { Accept: 'text/event-stream', 'Cache-Control': 'no-cache', 'Connection': 'keep-alive' } }`.

affects: >=1.0.0

Errors

Common errors & fixes

ReferenceError: require is not defined in ES module scope

Attempting to use CommonJS `require()` syntax in an ESM-only project, or an older Node.js environment that does not fully support ESM.

fix

Use `import { parse } from 'event-stream-parser';` for importing. Ensure your Node.js version is >=18 and your project is configured for ESM (e.g., `"type": "module"` in `package.json`).

TypeError: response.body is null

The `fetch` API returned a response without a readable body, which can happen if the server did not respond with a stream, or if the `Content-Type` was not `text/event-stream` as expected.

fix

Verify the server endpoint is correctly configured to send Server-Sent Events, and ensure your `fetch` request includes the `Accept: 'text/event-stream'` header.

TypeError: (intermediate value).pipeTo is not a function

This error occurs if you try to call `.pipeTo()` on the `Promise` returned by `parse()` instead of on the `ReadableStream` it resolves to.

fix

Always `await` the result of the `parse` function: `const eventStream = await parse(response.body);`.

Upgrade

Version history

1.0.2latest on npm

Audit

Dependencies

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Agent activity

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Resources

githubhttps://github.com/KEY60228/event-stream-parser ↗

packagehttps://www.npmjs.com/package/event-stream-parser ↗