Creating library inside Anuglar app to make reusable in another projects.

Making utils-lib library, default prefix fo selectors will be utils

$ ng g library utils-lib --prefix utils

Create simple directive in previously created library:

$ ng g d simple --project utils-lib --export

To export my simple directive from library in public-api.ts :

/*
 * Public API Surface of utils
 */
 
export * from './lib/simple.directive';
export * from './lib/utils-lib.module';

Build lib package

$ ng build utils-lib