backend/app/IonicUnit.js

const Unit = require('libflitter/Unit')
const cors = require('cors')
const Express = require('express')
const path = require('path')

class IonicUnit extends Unit {
    static get services() {
        return [...super.services, 'configs', 'express', 'canon', 'utility']
    }

    constructor(...args) {
        super(...args)

        /**
         * Fully qualified path to the root of the ionic app.
         * @type {string}
         */
        this.directory = path.resolve(path.dirname(this.utility.root()), this.configs.get('ionic.root'))
    }

    async go(app) {
        app.express.use(cors())

        app.express.use('/i', [
            // this.canon.get('middleware::auth:UserOnly'),
            (req, res, next) => {
                const allowed_extensions = ['.html', '.js', '.css', '.svg', '.ttf', '.jpg', '.png', '.jpeg']
                for ( const k1 in allowed_extensions ) {
                    if ( req.path.endsWith(allowed_extensions[k1]) ) return next()
                }

                return res.sendFile(path.resolve(this.directory, 'index.html'))
            },
            Express.static(this.directory),
        ])
    }

}

module.exports = exports = IonicUnit