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Verification, sanitization, and type coercion for environment variables in Node.js and web applications. Supports TypeScript! <br> <br>

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Contents

Install

npm

npm install env-var

yarn

yarn add env-var

Getting started

You can use env-var in both JavaScript and TypeScript!

Node.js Javascript example

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

// Or using module import syntax:
// import env from 'env-var'

const PASSWORD = env.get('DB_PASSWORD')
  // Throws an error if the DB_PASSWORD variable is not set (optional)
  .required()
  // Decode DB_PASSWORD from base64 to a utf8 string (optional)
  .convertFromBase64()
  // Call asString (or other APIs) to get the variable value (required)
  .asString();

// Read in a port (checks that PORT is in the range 0 to 65535)
// Alternatively, use a default value of 5432 if PORT is not defined
const PORT = env.get('PORT').default('5432').asPortNumber()

Node.js TypeScript example

import * as env from 'env-var';

// Read a PORT environment variable and ensure it's a positive integer.
// An EnvVarError will be thrown if the variable is not set, or if it
// is not a positive integer.
const PORT: number = env.get('PORT').required().asIntPositive();

WebApp Example

When using environment variables in a web application, usually your tooling such as vite imposes special conventions and doesn't expose process.env. Use from function to workaround this, and create an env object like so:

import { from } from 'env-var'

const env = from({
  BASE_URL: import.meta.env.BASE_URL,
  VITE_CUSTOM_VARIABLE: import.meta.env.CUSTOM_VARIABLE
})

For more examples, refer to the /example directory and EXAMPLE.md. A summary of the examples available in /example is written in the 'Other examples' section of EXAMPLE.md.

API

The examples above only cover a very small set of env-var API calls. There are many others such as asFloatPositive(), asJson() and asRegExp(). For a full list of env-var API calls, check out API.md.

You can also create your own custom accessor; refer to the 'extraAccessors' section of API.md.

Logging

Logging is disabled by default in env-var to prevent accidental logging of secrets.

To enable logging, you need to create an env-var instance using the from() function that the API provides and pass in a logger.

Using the Built-in Logger

The built-in logger will print logs only when NODE_ENV is not set to either prod or production.

const { from, logger } =  require('env-var')
const env = from(process.env, {}, logger)

const API_KEY = env.get('API_KEY').required().asString()

This is an example output from the built-in logger generated by running example/logging.js:

logging example output

Using a Custom Logger

If you need to filter env-var logs based on log levels (e.g. trace logging only) or have your own preferred logger, you can use a custom logging solution such as pino easily.

See the 'Custom logging' section of EXAMPLE.md for more information.

Optional integration with dotenv

You can optionally use dotenv with env-var.

There is no coupling between dotenv and env-var, but you can easily use them both together. This loose coupling reduces package bloat and allows you to start or stop using one without being forced to do the same for the other.

See the 'dotenv' section of EXAMPLE.md for more information.

Contributing

Contributions are welcomed and discussed in CONTRIBUTING.md. If you would like to discuss an idea, open an issue or a PR with an initial implementation.

Contributors