Auth0: a way to renew a token for Management API in a long-running script

example.js

const ManagementClient = require('auth0').ManagementClient
const Auth0TokenManager = require('./TokenManager')

const tokenManager = new Auth0TokenManager({
  domain: DOMAIN,
  clientId: CLIENT_ID,
  clientSecret: CLIENT_SECRET
})

tokenManager
  .getToken()
  .then(token => new ExtendedManagementClient({ domain: DOMAIN, token }))
  .then(client => /* do your things */ )

TokenManager.js

const jsonwebtoken = require('jsonwebtoken')
const request = require('superagent')
const Promise = require('bluebird')

class Auth0TokenManager {

  constructor (options) {
    this.domain = options.domain
    this.clientId = options.clientId
    this.clientSecret = options.clientSecret

    this._cachedToken = null
  }

  getToken () {
    if (this.isCachedTokenValid()) {
      return Promise.resolve(this._cachedToken)
    } else {
      return Promise.resolve(this.generateToken())
    }
  }

  generateToken (noCache = false) {
    console.log('Generate a new token')
    const url = `https://${this.domain}/oauth/token`
    return request
      .post(url)
      .send({
        grant_type: 'client_credentials',
        client_id: this.clientId,
        client_secret: this.clientSecret,
        audience: `https://${this.domain}/api/v2/`
      })
      .set('Accept', 'application/json')
      .then(res => res.body.access_token)
      .then(token => {
        if (!noCache) this._cachedToken = token
        return token
      })
  }

  isCachedTokenValid () {
    if (!this._cachedToken) return false

    const payload = jsonwebtoken.decode(this._cachedToken)

    const clockTimestamp = Math.floor(Date.now() / 1000)
    if (clockTimestamp >= payload.exp) {
      // expired
      return false
    }
    return true
  }
}

module.exports = Auth0TokenManager