processenv

processenv

processenv parses environment variables.

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Category	Status
Version
Dependencies
Dev dependencies
Build
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Installation

$ npm install processenv

Quick start

First you need to integrate processenv into your application:

const { processenv } = require('processenv');

If you use TypeScript, use the following code instead:

import { processenv } from 'processenv';

Then, to parse an environment variable, call the processenv function and provide the name of the environment variable you would like to parse:

const port = processenv('PORT');

Please note that the value is automatically converted to the appropriate data type, e.g. a number. This also works for stringified JSON objects, in case you want to store complex configuration data inside an environment variable.

Using default values

If you want to provide a default value, you may add it as a second parameter. This also works for booleans and all other types. If neither the environment variable nor the desired default value are set, processenv returns undefined:

const port = processenv('PORT', 3000);
const user = processenv('USER', 'Jane Doe');
const isRoot = processenv('ROOT', true);

Alternatively, you may also provide a function which returns the default values. This is useful, e.g. if you want to lazily evaluate a value:

const port = processenv('PORT', () => 3000);

If you want to use an asynchronous function, please note that you must await the call to processenv:

const port = await processenv('PORT', async () => 3000);

Using the ?? operator

Instead of providing a second parameter, you may use the ?? operator to handle default values:

const isRoot = processenv('ROOT') ?? true;

Please note that this is only true if you are using the ?? operator. If you are using the old-style || operator instead, the previous line always returns true, no matter what the actual value of the ROOT environment variable is. To avoid this problem, either use the ?? operator or use the previously shown syntax using a second parameter to provide a default value.

Getting all environment variables

If you want to get all environment variables at once, omit the name and simply call processenv. The values will all be parsed, but you can not specify default values.

const environmentVariables = processenv();

Running the build

To build this module use roboter.

$ npx roboter

Changelog

3.0.1 (2019-12-04)

Bug Fixes

• Update roboter and tests to use the ?? operator. (#48) (5a02c5d)