Production variables

 environment.ts

export const environment = {
    production: false,
    serviceUrl: "https://localhost:5001"
};

environment.prod.ts

export const environment = {
    production: true,
    serviceUrl: "https://www.site.com"
};

ng build command compiles all project with environment.prod.ts file so if you sure environment.serviceUrl at any point of your code, it will be changed from localhost to site.com...