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3.3.0 • Public • Published

app-env 🕵️

What environment are you in?

CircleCI npm version Coverage Status License: MIT

Example code

Library to detect in which environment your app is working. Supports detection of following environments:

  • production
  • development
  • test
  • staging
  • ci
  • preview

If you need to support more environments see non standard environments

Allows to easy change of environments through env variables.

Use cases

  • changing configuration based on detected environment
  • changing application behavior for tests
  • ability to force detected env on your command


  • 👷 Built with Typescript with full types support
  • 📝 Supports wider spectrum of environments than just production and development
  • 🔥 Provides builder to easily change configs/flags/switchers in type safe manner


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npm install @pallad/app-env

When do I need it?

  • If you need to support more than 2 most common environments (production, development) in your app.
  • If you need to change app behavior, config, flags based on detected behavior
  • If you need an easy ability to change environment without affecting NODE_ENV
  • If you hate ugly process.env.NODE_ENV comparisons in your code

How is environment detected?

@pallad/app-env detects environment based on available env variables.

  1. If APP_ENV env variable is supported environment name (case-insensitive) then use it, otherwise move to next step.
  2. If NODE_ENV env variable is supported environment name (case-insensitive) then use it, otherwise move to next step.
  3. If CI environment is detected then it is ci, otherwise move to next step.
  4. Fallback to development

Based on that logic you can easily lib to use your desired environment by settings APP_ENV variable.

Run process in test environment

APP_ENV=test node some-process.js

Run process in staging environment. Note that NODE_ENV variable will be simply ignored.

APP_ENV=staging NODE_ENV=development node some-process.js



import * as e from '@pallad/app-env';

e.name; // 'test'
e.env; // 'test'


import * as e from '@pallad/app-env';


Flag helpers

import * as e from '@pallad/app-env';

e.is('production'); // true for production
e.isEnv('production'); // same as above

e.is('production', 'staging'); // true for production or staging
e.isEnv('production', 'staging'); // same as above

Value helpers

import * as e from '@pallad/app-env';

e.forEnv('production')('foo'); // returns "foo" for production, undefined otherwise
e.forEnv('production')('foo', 'bar'); // returns "foo" for production, "bar" otherwise

e.forEnv('production', 'staging')('foo'); // returns "foo" for production or staging, undefined otherwise
e.forEnv('production', 'staging')('foo', 'bar'); // returns "foo" for production or staging, "bar" otherwise

e.forDevelopment('foo'); // returns "foo" for development, undefined otherwise
e.forDevelopment('foo', 'bar'); // returns "foo" for development, "bar" otherwise


Advanced value builder

Ultimate helper of all helpers. Extends @pallad/builder.

import * as e from '@pallad/app-env';

const value = e.build()
	.forEnv(['production', 'test'], 'baz')
	.getOrDefault('wtf?'); // or just .get() to get value without default

Note that the order of chaining is important

const value = e.build()
	.forEnv(['development', 'test'], 'baz')
	.get(); // you'll get "foo" (not "baz") for development since it was first evaluated rule

Non standard environments

While library by default supports most of commonly known environment names sometimes you might have special environments that are not covered.

For such cases you can create your own configuration with custom names.

import {Configuration} from '@pallad/app-env';

const envConfig = new Configuration(['e2e', 'eu_region']);
const info = envConfig.create('e2e');

info.isEnv('e2e') // true
info.isProduction // false

envConfig.getEnvNameFromProcess(); // e2e or eu_region might be properly detected

Note that old environment names like production, development, CI etc are still available.

Such created instance of Configuration allows you to create env info, value builder and detect env from environment variables and accepting new environment names.

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npm i @pallad/app-env

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