declare const production: any;
export default production;

config.plugins.push(
new DefinePlugin({
     'production': env.prod === 'true'
  }),
...
)

import isProduction from '../../environment/isProduction';

// Main Http module looks like
@NgModule({
    imports: [HttpCustomModule],
    providers: [
        {
            provide: CustomersService,
            useFactory: (httpClient: HttpClient) => {
                return isProduction
                    ? new CustomersHttpService(httpClient)
                    : new CustomersService(httpClient);
            },
            deps: [HttpClient]
        },
        {
            provide: ProfilesService,
            useClass: isProduction ? ProfilesHttpService : ProfilesService,
            deps: [HttpClient]
        },
        ...

})
export class HttpBackendModule { }

import { NgModule, isDevMode } from '@angular/core';

"scripts": {
        "build-app:dev": "webpack --mode development --config webpack.config.app.babel.js --env.prod=true --watch",
        "build-app:prod": "webpack --mode production --config webpack.config.app.babel.js --env.prod=true",