Browser compatibility

Server-sent events is supported natively by all modern browsers.

You can safely use the EventSource interface without having to add any extra dependencies to your front-end code bundle.

Nevertheless, should you need to support older browsers or need additional features not supported by the native implementation, some polyfills are listed below.

Can I Use…

Can I use… Server-sent events

Polyfills

lukas-reining/eventsource

EventSource implementation that is fully compliant with the WHATWG Server-Sent Events specification but takes more arguments.

• Usable in browser and Node.js environments (uses the Fetch API)
• TypeScript types
• Custom HTTP method
• Custom headers
• Custom retry time
• Automatic logging

joshmossas/event-source-plus

A more configurable EventSource implementation that runs in browsers, NodeJS, and workers.

• Usable in browser, Node.js and worker environments (uses the Fetch API)
• TypeScript types
• Custom HTTP method
• Custom headers
• Custom URL search parameters
• Custom retry time and strategies

mpetazzoni/sse.js

A flexible EventSource replacement for JavaScript designed to consume Server-Sent Events (SSE) streams with more control and options than the standard EventSource.

• TypeScript types
• Custom HTTP method
• Custom headers
• Control when request is initiated

Azure/fetch-event-source

Or its fork: ai-zen/node-fetch-event-source

A better API for making Event Source requests, with all the features of fetch()

• TypeScript types
• Custom HTTP method
• Custom headers
• Custom retry time and strategies

Yaffle/EventSource

A polyfill for EventSource.

• Custom headers
• Custom Last-Event-ID query parameter name

amvtek/EventSource

Provides a polyfill to support EventSource in browsers where it is not available.

• Custom headers
• Custom URL search parameters
• Automatic logging