ble-server/ble/time-characteristic.js

const bleno = require('bleno')
const config = require('./config.json')

class TimeCharacteristic extends bleno.Characteristic {
  constructor() {
    super({
      uuid: config.uuid.service.func.time,
      properties: ['read'],
      descriptors: [
        new bleno.Descriptor({
          uuid: '88ff',
          value: 'Now Time'
        })
      ]
    })
  }

  onReadRequest(offset, callback) {
    console.log(`offset :: ${offset}`)
    callback(this.RESULT_SUCCESS, new Buffer(`${Date.now()}`))
  }
}

module.exports = TimeCharacteristic