plugins.js

const { readFileSync } = require('fs');

const envPlugin = {
  name: 'env',
  setup(build) {
    build.onResolve({ filter: /@app\/env$/ }, (args) => {
      return {
        path: args.path,
        namespace: 'env-ns',
      };
    });

    build.onLoad({ filter: /.*/, namespace: 'env-ns' }, () => {
      const envFile = process.env.NODE_ENV ? `.${process.env.NODE_ENV}` : '';
      const content = readFileSync(
        `../../environments/environment${envFile}.ts`,
        'utf8'
      );

      return {
        contents: content,
        resolveDir: '../../environments',
        loader: 'ts',
      };
    });
  },
};

module.exports = [envPlugin];