express-sse/README.md

An Express middleware for Server-Sent Events (EventSource)

express-sse
============

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An Express middleware for quick'n'easy server-sent events.

## About
`express-sse` is meant to keep things simple. You need to send server-sent events without too many complications and fallbacks? This is the library to do so.

## Installation:
`npm install --save express-sse`

or

`yarn add express-sse`

## Usage example:
### Options:
You can pass an optional options object to the constructor. Currently it only supports changing the way initial data is treated. If you set `isSerialized` to `false`, the initial data is sent as a single event. The default value is `true`.

```js
var sse = new SSE(["array", "containing", "initial", "content", "(optional)"], { isSerialized: false, initialEvent: 'optional initial event name' });
```

### Server:
```js
var SSE = require('express-sse');
var sse = new SSE(["array", "containing", "initial", "content", "(optional)"]);

...

app.get('/stream', sse.init);

...

sse.send(content);
sse.send(content, eventName);
sse.send(content, eventName, customID);
sse.updateInit(["array", "containing", "new", "content"]);
sse.serialize(["array", "to", "be", "sent", "as", "serialized", "events"]);
```

### Client:
```js
var es = new EventSource('/stream');

es.onmessage = function (event) {
  ...
};

es.addEventListener(eventName, function (event) {
  ...
});
```