Nodejs

Cookies

  • httpOnly attribute is used with cookies to restrict access from the client side.
ctx.res.cookie("token", token, { httpOnly: true });

Headers

Access-Control-Allow-Origin

  • Make api available to differenct hostname.
const cors = require('cors');
const app = express();
app.use(cors());

Access-Control-Expose-Headers

  • Make browser available to read headers.
app.use(cors({
    exposedHeaders: ['Content-Disposition']
}));
  • Read filename from header of download api.
fetch("/download").then(async (res) => {
  const filename = res.headers
    .get("Content-Disposition")
    .match(/filename="(?<filename>.*?)"/);

  return {
    filename: filename.groups.filename,
    file: await res.blob(),
  };
});

Express

const express = require('express');
const app = express();
const port = 8000
app.listen(port, () => {
  console.log(`app listening on port ${port}`)
})
  • Route parameters
app.get('/shortLink/:Id', (req, res) => {
  res.send(req.params)
})
  • Download file
app.get('/download', function(req, res) {
  res.download('./file.txt','download.txt');
});

Websocket

npm init -y
npm install express ws
  • add app.js with following sample code and run node app.js
const express = require('express')
const SocketServer = require('ws').Server
const PORT = 3000

const server = express().listen(PORT, () => {
    console.log(`Listening on ${PORT}`)
})

const wss = new SocketServer({ server })
wss.on('connection', ws => {
    console.log('Client connected')

    ws.on('message', data => {
        data = data.toString()  
        console.log(data)

        ws.send(data)

        wss.clients.forEach(client => {
            client.send(data)
        })
    })

    ws.on('close', () => {
        console.log('Close connected')
    })
})

  • connect websocket in client :

      const ws = new WebSocket('ws://localhost:3000')

  ws.onopen = () => {
      console.log(ws.readyState)
  }
  ws.onclose = () => {
      console.log(ws.readyState);
  }
  ws.onmessage = event => {
      console.log(JSON.parse(event.data))
  }

  // ws.close() //close websocket