"environmentSource": "environments/environment.ts",
      "environments": {
        "dev": "environments/environment.dev.ts",
        "build": "environments/environment.build.ts",
        "uat": "environments/environment.uat.ts",
        "prod": "environments/environment.prod.ts"
      }

...

import { environment } from '../../../environments/environment';

...

var ev = environment.apiBaseUrl;