how to use sequlize with webpack?

I am using Webpack. after build sequelize is not connect with DB. How to use Webpack with sequelize ?

const fs = require('fs');
const path = require('path');
const Sequelize = require('sequelize');
const basename = path.basename(__filename);
const env = process.env.NODE_ENV || 'development';
const config = require(__dirname + '/../config/config.js')[env];
const db = {};

let sequelize;
if (config.use_env_variable) {
    sequelize = new Sequelize(process.env[config.use_env_variable], config);
} else {
    sequelize = new Sequelize(config.database, config.username, config.password, config);
}
fs.readdirSync(__dirname)
    .filter((file) => {
        return file.indexOf('.') !== 0 && file !== basename && file.slice(-3) === '.js';
    })
    .forEach((file) => {
        const model = require(path.join(__dirname, file))(sequelize, Sequelize.DataTypes);
        db[model.name] = model;
    });

Object.keys(db).forEach((modelName) => {
    if (db[modelName].associate) {
        db[modelName].associate(db);
    }
});

db.sequelize = sequelize;
db.Sequelize = Sequelize;

module.exports = db;

Himanshu Rajput