@gabrielmethot/node-env-parser NPM

node-env-parser

Utility functions to parse Node.js-like environment variables to type-checked values.

import { EnvironmentParser } from "@gabrielmethot/node-env-parser";

process.env = {
  VERSION: "2.1",
  TOGGLE_FEATURE: "true",
};

const parser = new EnvironmentParser(process.env);

const NODE_ENV: string = parser.parseString("NODE_ENV", {
  default: "development",
});

const VERSION: number = parser.parseNumber("VERSION", {
  default: 1,
  parser: (value) => parseFloat(value),
});

const TOGGLE_FEATURE: boolean = parser.parseBoolean("TOGGLE_FEATURE");

// { NODE_ENV: "development", VERSION: 2.1, TOGGLE_FEATURE: true }
console.log({ NODE_ENV, VERSION, TOGGLE_FEATURE });

Installing

$ npm install @gabrielmethot/node-env-parser

Error handling

If an environment variable is defined, then it must be a string that can be parsed using the provided parsing function. Otherwise, it throws an error.

import { EnvironmentParser } from "@gabrielmethot/node-env-parser";

process.env = {
  TOGGLE_FEATURE_A: "true",
  TOGGLE_FEATURE_B: "No Thanks!",
};

const parser = new EnvironmentParser(process.env);
parser.parseBoolean("TOGGLE_FEATURE_A"); // Returns true
parser.parseBoolean("TOGGLE_FEATURE_B"); // Throws a ConversionError

If an environment variable is undefined, then a default value must be provided. Otherwise, it throws an error.

import { EnvironmentParser } from "@gabrielmethot/node-env-parser";

process.env = {};

const parser = new EnvironmentParser(process.env);
parser.parseString("SOME_VALUE", { default: "Hello World!" }); // Returns "Hello World!"
parser.parseString("SOME VALUE"); // Throws a UndefinedError