Simple Way to Implement Server Sent Events in Node.js?

前端未结

关注

 6  1291

I\'ve looked around and it seems as if all the ways to implement SSEs in Node.js are through more complex code, but it seems like there should be an easier way to send and recei

相关标签:

6条回答

北荒

2021-01-31 06:35

Here is an express server that sends one Server-Sent Event (SSE) per second, counting down from 10 to 0:

const express = require('express')

const app = express()
app.use(express.static('public'))

app.get('/countdown', function(req, res) {
  res.writeHead(200, {
    'Content-Type': 'text/event-stream',
    'Cache-Control': 'no-cache',
    'Connection': 'keep-alive'
  })
  countdown(res, 10)
})

function countdown(res, count) {
  res.write("data: " + count + "\n\n")
  if (count)
    setTimeout(() => countdown(res, count-1), 1000)
  else
    res.end()
}

app.listen(3000, () => console.log('SSE app listening on port 3000!'))

Put the above code into a file (index.js) and run it: node index

Next, put the following HTML into a file (public/index.html):

<html>
<head>
  <script>
  if (!!window.EventSource) {
    var source = new EventSource('/countdown')

    source.addEventListener('message', function(e) {
      document.getElementById('data').innerHTML = e.data
    }, false)

    source.addEventListener('open', function(e) {
      document.getElementById('state').innerHTML = "Connected"
    }, false)

    source.addEventListener('error', function(e) {
      const id_state = document.getElementById('state')
      if (e.eventPhase == EventSource.CLOSED)
        source.close()
      if (e.target.readyState == EventSource.CLOSED) {
        id_state.innerHTML = "Disconnected"
      }
      else if (e.target.readyState == EventSource.CONNECTING) {
        id_state.innerHTML = "Connecting..."
      }
    }, false)
  } else {
    console.log("Your browser doesn't support SSE")
  }
  </script>
</head>
<body>
  <h1>SSE: <span id="state"></span></h1>
  <h3>Data: <span id="data"></span></h3>
</body>
</html>

In your browser, open localhost:3000 and watch the SSE countdown.

0 讨论(0)

慢半拍i

2021-01-31 06:40

**client.js**

var eventSource = new EventSource("/route/events");
eventSource.addEventListner("ping", function(e){log(e.data)});

//if no events specified
eventSource.addEventListner("message", function(e){log(e.data)});

**server.js**

http.createServer((req, res)=>{

    if(req.url.indexOf("/route/events")>=){

      res.setHeader('Connection', 'keep-alive');

      res.setHeader("Cache-Control", "no-cache");

      res.setHeader("Content-Type", "text/event-stream");

      let event = "event: ping";

      let id = `id: ${Date.now()}`;

      let data = {
         message:`hello @${new Date().toString()}`
      }

      data = "data: "+JSON.stringify(data);

      res.end(`${event}\n${id}\n${data}\n\n`);
   }
}).listen(PORT)

0 讨论(0)

离开以前

2021-01-31 06:42

You should be able to do such a thing using Socket.io. First, you will need to install it with npm install socket.io. From there, in your code you will want to have var io = require(socket.io);

You can see more in-depth examples given by Socket.IO

You could use something like this on the server:

var express = require('express');
var app = express();
var server = require('http').createServer(app);
var io = require('../..')(server);
var port = process.env.PORT || 3000;

server.listen(port, function () {
  console.log('Server listening at port ' + port);
});

app.use(express.static(__dirname + '/public'));

io.on('connection', function (socket) {
    socket.emit('EVENT_NAME', {data});
});

And something like this on the client:

<script src="socket_src_file_path_here"></script>
<script>
  var socket = io('http://localhost');
  socket.on('EVENT_NAME', function (data) {
    console.log(data);
    //Do whatever you want with the data on the client
  });
</script>

0 讨论(0)

渐次进展

2021-01-31 06:44

If you're using express this is the easiest way https://www.npmjs.com/package/express-sse

on BE:

const SSE = require('express-sse');

const sse = new SSE();

...

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

...

sse.send('message', 'event-name');

on FE:

const EventSource = require('eventsource');

const es = new EventSource('http://localhost:3000/sse');

es.addEventListener('event-name', function (message) {
  console.log('message:', message)
});

0 讨论(0)

北恋

2021-01-31 06:45

I'm adding a simple implementation of SSE here. It's just one Node.js file.

You can have a look at the result here: https://glossy-ox.glitch.me/

const http = require('http');
const port = process.env.PORT || 3000;

const server = http.createServer((req, res) => {
  // Server-sent events endpoint
  if (req.url === '/events') {
    res.writeHead(200, {
      'Content-Type': 'text/event-stream',
      'Cache-Control': 'no-cache',
      'Connection': 'keep-alive',
    });

    const refreshRate = 1000; // in milliseconds
    return setInterval(() => {
      const id = Date.now();
      const data = `Hello World ${id}`;
      const message =
        `retry: ${refreshRate}\nid:${id}\ndata: ${data}\n\n`;
      res.write(message);
    }, refreshRate);
  }

  // Client side
  res.writeHead(200, {'Content-Type': 'text/html'});
  res.end(`
    <!DOCTYPE html>
    <html lang="en" dir="ltr">
      <head>
        <meta charset="utf-8">
        <title>SSE</title>
      </head>
      <body>
        <pre id="log"></pre>
      </body>
      <script>
        var eventSource = new EventSource('/events');
        eventSource.onmessage = function(event) {
          document.getElementById('log').innerHTML += event.data + '<br>';
        };
      </script>
    </html>
  `);
});

server.listen(port);

server.on('error', (err) => {
  console.log(err);
  process.exit(1);
});

server.on('listening', () => {
  console.log(`Listening on port ${port}`);
});

0 讨论(0)

小蘑菇

2021-01-31 06:47

I found SSE implementation in node.js.

Github link: https://github.com/einaros/sse.js

NPM module:https://www.npmjs.com/package/sse

Will above link helps you ?

0 讨论(0)
发布评论:

提交评论
- 加载中...