server.js

const express = require('express')
const next = require('next')
const Featureflow = require('featureflow-node-sdk');
const LaunchDarkly = require('ldclient-node');

const dev = process.env.NODE_ENV !== 'production'
const app = next({ dev })
const handle = app.getRequestHandler()
const ldclient = LaunchDarkly.init(process.env.LD_SDK_KEY)
const featureflow = new Featureflow.Client({ apiKey: 'srv-env-685e066dea464f88be14effbf65cf69c' });
app.prepare()
  .then(() => {
    const server = express()
    server.use((req, res, next) => {

      let user = {
        'key': 'user1',
        'country': 'AU',
        'custom': {
          'page': 'index',
          'roles': ['USER_ADMIN', 'BETA_CUSTOMER']
        }
      }

      // let user = new Featureflow.UserBuilder("user1")
      //   .withAttribute('country', 'US')
      //   .withAttribute('page', 'index')
      //   .withAttributes('roles', ['USER_ADMIN', 'BETA_CUSTOMER'])
      //   .build();

      // Using allFlagsState https://docs.launchdarkly.com/docs/node-sdk-reference#section-all-flags
      // ldclient.on('ready', function () {
      //   ldclient.allFlagsState(user).then((allFlags) => {
      //     console.log(allFlags);
      //     req.features = allFlags;
      //   }
      //   )
      // });
      allFlags = ldclient.allFlagsState(user).then((allFlags) => {
        req.features = allFlags;
      });
      return next();
    });

    server.get('/api/features', (req, res) => {
      let user = {
        'key': 'user2',
        'country': 'AU',
        'custom': {
          'page': 'post',
          'roles': ['USER_ADMIN', 'BETA_CUSTOMER']
        }
      }

      allFlags = ldclient.allFlagsState(user).then((allFlags) => {
        res.json(allFlags.toJSON());
      });

      // ldclient.on("ready", () => {
      //   ldclient.allFlagsState(user).then((allFlags) => {
      //     res.json(allFlags);
      //   }).catch(err => {
      //     console.log(err);
      //     res.status(500).send(err);
      //   })
      // })
      // let user = new Featureflow.UserBuilder("user2")
      //   .withAttribute('country', 'US')
      //   .withAttribute('page', 'post')
      //   .withAttributes('roles', ['USER_ADMIN', 'BETA_CUSTOMER'])
      //   .build();
      //res.json(featureflow.evaluateAll(user));
    })

    server.get('*', (req, res) => {
      return handle(req, res)
    })

    server.listen(3000, (err) => {
      if (err) throw err
      console.log('> Ready on http://localhost:3000')
    })
  })
  .catch((ex) => {
    console.error(ex.stack)
    process.exit(1)
  })