The eventsource-parser npm package is a utility for parsing Server-Sent Events (SSE) streams. It allows you to handle real-time data streams from servers efficiently by parsing the incoming data into manageable events.

What are eventsource-parser's main functionalities?

Parsing SSE Streams

This feature allows you to parse incoming SSE data streams. The `createParser` function initializes a parser that processes incoming data and triggers a callback for each event.

const { createParser } = require('eventsource-parser');

const parser = createParser((event) => {
  if (event.type === 'event') {
    console.log('Received event:', event);
  }
});

const sseData = `data: Hello\n\n`;
parser.feed(sseData);

Handling Different Event Types

This feature allows you to handle different types of events, such as comments and data events. The parser can differentiate between these types and process them accordingly.

const { createParser } = require('eventsource-parser');

const parser = createParser((event) => {
  if (event.type === 'event') {
    console.log('Received event:', event);
  } else if (event.type === 'comment') {
    console.log('Received comment:', event);
  }
});

const sseData = `: This is a comment\ndata: Hello\n\n`;
parser.feed(sseData);

Error Handling

This feature demonstrates how to handle errors that may occur during the parsing of SSE data. The parser can throw errors if the data is not in the correct format, and you can catch these errors to handle them gracefully.

const { createParser } = require('eventsource-parser');

const parser = createParser((event) => {
  if (event.type === 'event') {
    console.log('Received event:', event);
  }
});

try {
  const invalidSseData = `data: Hello\ninvalid\n`;
  parser.feed(invalidSseData);
} catch (error) {
  console.error('Error parsing SSE data:', error);
}

Other packages similar to eventsource-parser

Changelog

Source

1.0.0 (2023-03-23)

⚠ BREAKING CHANGES

improve ESM/CJS compatibility, require node 14 or higher

Code Refactoring

improve ESM/CJS compatibility, require node 14 or higher (26d630e)

Readme

Source

eventsource-parser

A streaming parser for server-sent events/eventsource, without any assumptions about how the actual stream of data is retrieved. It is intended to be a building block for clients and polyfills in javascript environments such as browsers, node.js and deno.

You create an instance of the parser, and feed it chunks of data - partial or complete, and the parse emits parsed messages once it receives a complete message.

Installation

npm install --save eventsource-parser

Usage

import {createParser, ParsedEvent, ReconnectInterval} from 'eventsource-parser'

function onParse(event: ParsedEvent | ReconnectInterval) {
  if (event.type === 'event') {
    console.log('Received event!')
    console.log('id: %s', event.id || '<none>')
    console.log('name: %s', event.name || '<none>')
    console.log('data: %s', event.data)
  } else if (event.type === 'reconnect-interval') {
    console.log('We should set reconnect interval to %d milliseconds', event.value)
  }
}

const parser = createParser(onParse)
const sseStream = getSomeReadableStream()

for await (const chunk of sseStream) {
  parser.feed(chunk)
}

// If you want to re-use the parser for a new stream of events, make sure to reset it!
parser.reset()
console.log('Done!')

License

Keywords

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Package last updated on 28 Jan 2023

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