ble-server/app.js

const bleno = require('bleno')
const config = require('./config.json')
const adapterName = 'BLE_Printer'
const serverUUID = config.uuid.main
const localEvent = require('./localEvent')
const fs = require('fs')
const MainService = require('./main-service')

const printer = require('./PrinterDev')

bleno.on('stateChange', state => {
  console.log(`bt device state ${state}`)
  if (state == 'poweredOn') {

    bleno.startAdvertising(adapterName, [serverUUID], (error) => {

    })
  } else {
    bleno.stopAdvertising()
  }
})

bleno.on('advertisingStart', function (error) {
  console.log('on -> advertisingStart: ' + (error ? 'error ' + error : 'success'));

  if (!error) {
    bleno.setServices([new MainService()], error => {
      console.log('set service', error)
    })
  }
})

localEvent.on('print', async (str) => {
  let status = false
  if (printer.isOpen) {
    try {
      status = await printer.printerString(str)
    } catch (err) {
      status = false
    }
  }

  localEvent.emit('printResult', status)
})