Serve a 1px gif using express

gif.js

const app = require('express')()

app.get('/gif', (req, res) => {
  const data = [
    0x47,0x49, 0x46,0x38, 0x39,0x61, 0x01,0x00, 0x01,0x00, 0x80,0x00, 0x00,0xFF, 0xFF,0xFF,
    0x00,0x00, 0x00,0x21, 0xf9,0x04, 0x04,0x00, 0x00,0x00, 0x00,0x2c, 0x00,0x00, 0x00,0x00,
    0x01,0x00, 0x01,0x00, 0x00,0x02, 0x02,0x44, 0x01,0x00, 0x3b
  ]
  
  return res
    .set('Content-Type', 'image/gif')
    .set('Content-Length', data.length)
    .status(200)
    .send(new Buffer(data))
})

app.listen(3000 || process.env.PORT)