Get-env NPM | npm.io

get-env

get-env is a Node.js library returning dev, prod, or optional extra environments based on process.env.NODE_ENV.

get-config uses this library to parse process.env.NODE_ENV.

Why use this library?

Many people use the following simple line of code, but there are some disadvantages to this approach:

const env = process.env.NODE_ENV || 'development';

If your code tests against, development and production (for example), then you must only use those values for NODE_ENV. get-env library accepts multiple alternative values as rules for an environment, therefore you can make unlimited number of aliases to the same environment same. This lets you forget about the exact string value you used in your code, which means you can use whatever value that comes naturally to your mind whenever you switch environments. All environment names matched by this library are case-insensitive as well.
If you supply an unregistered value for NODE_ENV (for example, productoin instead of production -- that is a typo), the env variable is now set to this wrong value and the rest of code that tests against this variable would have an unexpected behavior. This library fixes this problem by throwing an error on unregistered and non-empty value set to NODE_ENV. An empty value is resolved to dev environment.
If you start adding more extra environments (ex: staging, test, etc.) then it won't be a simple one line of code anymore. This library provides consistent, straightforward, and flexible extra environment addition methods therefore you can freely add or remove environments with minimal overhead in your code while keeping all the above mentioned benefits.

Basically, this library provides a consistent, reliable, scalable way to parse the NODE_ENV environment variable so it is ready for you to use from an app targetting multiple environments.

Examples

The following single line of code ...

const env = require('get-env')();

... is equivalent to ...

const nodeEnv = (process.env.NODE_ENV || '').toLowerCase();
var env;
if (nodeEnv === 'prod' || nodeEnv === 'production') {
  env = 'prod';
} else if (nodeEnv === 'dev' || nodeEnv === 'development' || nodeEnv === '') {
  env = 'dev';
} else {
  throw new Error('Unknown environment name: NODE_ENV=' + nodeEnv);
}

For slightly more complex example, the following lengthy code ...

const nodeEnv = process.env.NODE_ENV;
var env;
if (nodeEnv === 'production' || nodeEnv === 'prod') {
  env = 'prod';
} else if (nodeEnv === 'staging') {
  env = 'staging';
} else if (nodeEnv === 'test' || nodeEnv === 'testing') {
  env = 'test';
} else if (nodeEnv === 'dev' || nodeEnv === 'development' || !nodeEnv) {
  env = 'dev';
} else {
  throw new Error('Unknown environment name: NODE_ENV=' + nodeEnv);
}

... can be simplified to ...

const env = require('get-env')({
  staging: 'staging',
  test: ['test', 'testing']
});

Matching rules for `process.env.NODE_ENV`

There are 2 pre-registered environments: dev and prod.
prod is returned when any of the following values are set: prod, production
dev is returned when the value is empty (default environment) or any of the following values are set: dev, development
It throws an error when the value is unregistered and non-empty. (catches typos)
It always expects a case-insensitive value. (i.e. NODE_ENV=PROD is equivalent to NODE_ENV=prod)
Extra environments can be optionally added in various methods. (see the usage section below)

Installation

$ npm install get-env

Usage

const env = require('get-env')();

This returns either dev or prod. (pre-registered environments)

Extra environments can be optionally added in addition to the pre-registered environments (dev and prod) with any of the following methods:

1. Pass a string

const env = require('get-env')('test');

Return test when the value is TEST.
Otherwise, return dev or prod. (default rules apply)

2. Pass multiple strings as arguments or an array

const env = require('get-env')('docker', 'test');
// OR
const env = require('get-env')(['docker', 'test']);

Return docker when the value is DOCKER.
Return test when the value is TEST.
Otherwise, return dev or prod. (default rules apply)

3. Pass a plain object

const env = require('get-env')({
  docker: 'docker',  // or 'DOCKER'
  test: ['test', 'testing'],  // or ['TEST', 'TESTING']
  prod: ['pr', 'prod', 'production']  // or ['PR', 'PROD', 'PRODUCTION']
});

Return docker when the value is docker.
Return test when the value is test or testing.
Return prod when the value is pr, prod, or production. (pre-reigstered rules for prod are overriden)
Otherwise, return dev.