how can we use environment variable in angular version >=2

Question

I am now reading the angular4 doc, and noticed, there is one folder, environments, and under which, there are multiple environment files, such as environment.ts, environment

Answer 1

If you are using CLI then in .angular-cli.json file, place this code. (From angular 6 onward, .angular-cli.json file is renamed to .angular.json)

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

In dev environment file, you can write

export const environment = {
production: false,
url: 'http://something.com'
};

And in prod environment file, you can write

export const environment = {
production: true,
url: 'http://something.com'
}

In components or services, you can use like

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

You can command:

ng serve --dev     // Or 
ng serve --prod

Note: you should have environments directory directly in app directory and both environment files should be there.