The Server-Sent Events specification describes a built-in class EventSource, that keeps connection with the server and allows to receive events from it.

Similar to WebSocket, the connection is persistent.

But there are several important differences:

EventSource is a less-powerful way of communicating with the server than WebSocket.

Why should one ever use it?

The main reason: it’s simpler. In many applications, the power of WebSocket is a little bit too much.

We need to receive a stream of data from server: maybe chat messages or market prices, or whatever. That’s what EventSource is good at. Also it supports auto-reconnect, something we need to implement manually with WebSocket. Besides, it’s a plain old HTTP, not a new protocol.

• Step-1

npm install

• Step-2

npm start

• Step-3: Open below url in the browser

http://localhost:5000