How can a web page read from the user's serial port - in the year 2017?

Question

I have to re-implement an existing system from scratch.

At one point, when the user navigates to a certain web page the server must read data from the user\'s seria

Answer 1

Using the serialport package through Node JS as a server is an option. This works on Windows, and apparently on Linux and OSX as well. See https://github.com/node-serialport/node-serialport.

This is a solution I have used to read micro bit comms through USB to a browser. I did have to rebuild the driver for windows (10) with:

• npm install --global --production windows-build-tools
• npm install serialport --build-from-source

I've pasted some of my code below for reference:

const serialport = require('serialport')

// list serial ports:
const find_microbit = (error, success) => {
  serialport.list((err, ports) => {
    if (err) {
      error(err)
    } else {
      let comName = null
      ports.forEach((port) => {
        if ((port.vendorId == '0D28') && (port.productId == '0204')) {
          comName = port.comName
        }
      })
      if (comName != null) {
        success(comName)
      } else {
        error('Could not find micro:bit.')
      }
    }
  })
}

exports.get_serial = (error, success) => {
  find_microbit(error, (comName) => {
    let serial = new serialport(comName, {baudRate: 115200, parser: serialport.parsers.readline('\n')}, (err) => {
      if (err) {
        error(err)
      } else {
        success(serial)
      }
    })
  })
}
/* e.g.
get_serial((err)=>{console.log("Error:" + err)},
    (serial)=>{
        serial.on('data', (data) => {
            let ubit = JSON.parse(data)
            if (ubit.button == 'a') {
                console.log('Button A Pressed')
            }
            if (ubit.button == 'b') {
                console.log('Button B Pressed')
            }
            if (ubit.ir) {
                console.log('Visitor detected')
            }
        })
    })
    */

This approach works - for me - but it can be time consuming to get it working. It's not, to my mind, an obvious, or simple solution. It requires a fair amount of technical know how - and is, I feel, much more complex and 'tricky' than it should be.

In particular - rebuilding the library isn't something I would expect to do when using Node JS. One of the possible effects is that you would need to rebuild the serial port binaries for a different platform.