How To Use Environment Variables in Angular

If you would like to follow along with this article, you will need:

• A local development environment for Node.js. Follow How to Install Node.js and Create a Local Development Environment.

This tutorial was verified with Node v16.2.0, npm v7.15.1, and @angular/core v12.0.3.

Angular CLI projects already use a production environment variable to enable production mode when in the production environment:

// ...

if (environment.production) {
  enableProdMode();
}

Angular also provides us with an utility function called isDevMode that makes it possible to check if the app in running in dev mode:

import { Component, OnInit, isDevMode } from '@angular/core';

@Component({ ... })
export class AppComponent implements OnInit {
  ngOnInit() {
    if (isDevMode()) {
      console.log('Development!');
    } else {
      console.log('Production!');
    }
  }
}

This example code will log out the message 'Development! in development mode and log out the message Production! in production mode.

And you’ll also notice that by default in the /src/environment folder you have an environment file for development and one for production.

Let’s say we want to use a different key depending on if we’re in development or production mode:

For development settings in environment.ts:

export const environment = {
  production: false,
  apiKey: 'devKey'
};

For production settings in environment.prod.ts:

export const environment = {
  production: true,
  apiKey: 'prodKey'
};

And in our component all we have to do in order to access the variable is the following:

import { Component } from '@angular/core';
import { environment } from '../environments/environment';

Angular takes care of swapping the environment file for the correct one.

Run development mode with:

ng serve

The apiKey variable resolves to devKey.

Run production mode with:

ng serve --configuration=production

The apiKey variable resolves to prodKey.

Add new environments in Angular CLI projects by adding new entries to the configurations field in the angular.json file.

Let’s add a staging environment based on the configuration used by production:

{
  // ...
  "projects": {
    "angular-environment-example": {
      // ...
      "prefix": "app",
        "build": {
          // ...
          "configurations": {
            "staging": {
              // ...
              "fileReplacements": [
                {
                  "replace": "src/environments/environment.ts",
                  "with": "src/environments/environment.stage.ts"
                }
              ],
              // ...
            },
            // ...
          },
        },
        "serve": {
          "builder": "@angular-devkit/build-angular:dev-server",
          "configurations": {
            "staging": {
              "browserTarget": "angular-environment-example:build:staging"
            },
          }
        },
      }
    }
  }
}

And now we can add a staging environment file:

export const environment = {
  production: true,
  apiKey: 'stagingKey'
};

Run development mode with:

ng serve --configuration=staging

The apiKey variable will resolve to stagingKey.

In this tutorial, you learned how to use environment variables in Angular.

If you’d like to learn more about Angular, check out our Angular topic page for exercises and programming projects.