Nodejs process.env

Summary: in this tutorial, you’ll learn how to read the environment variables using the Node.js process.env property of the process module.

Introduction to the node.js process module

The process is a core module of Node.js. The process module has the env property that contains all the environment variables.

To set an environment variable on Windows, you use the SET command. For example:

SET NODE_ENV=developmentCode language: JavaScript (javascript)

On macOS or Linux, you use the EXPORT command:

EXPORT NODE_ENV=developmentCode language: JavaScript (javascript)

In this syntax, the NODE_ENV is an environment variable with the value 'development'.

To get access the NODE_ENV in Node.js, you use the process.env like this:

process.env.NODE_ENVCode language: JavaScript (javascript)

In this example, the proces.env.NODE_ENV returns the string 'development'.

If the NODE_ENV is not set, the process.env.NODE_ENV will return undefined.

The following statement uses the logical OR operator to return the current Node.js environment or development if the NODE_ENV is not set:

const nodeEnv = process.env.NODE_ENV || 'development';Code language: JavaScript (javascript)

It’s a good practice to store credential information such as database username and password in the environment variables.

Let’s see some practical examples of using the Node.js process.env.

Using environment variables to store credential information securely

The following example shows you how to use the process.env to access the current Node.js environment and load the configuration accordingly.

The project structure will look like this:

├── config
|  ├── app.js
|  ├── development.js
|  └── production.js
├── index.js
└── package.jsonCode language: plaintext (plaintext)

First, create a new folder named env.

Second, run the npm init command to initialize a new package:

npm init --yesCode language: JavaScript (javascript)

Third, create a new folder called config inside the project root directory:

mkdir configCode language: JavaScript (javascript)

Fourth, create three files app.js, development.js, and production.js in the config folder. The development.js stores the database credentials in the development environment:

module.exports = {
    database: {
        host: "localhost",
        port: 27017,
        username: "admin",
        password: "Password1",
    },
};Code language: JavaScript (javascript)

The production.js file stores the same information as the development.js. However, it uses the environment variables instead:

module.exports = {
    database: {
        host: process.env.DB_HOST,
        port: process.env.DB_PORT,
        username: process.env.DB_USERNAME,
        password: process.env.DB_PASSWORD,
    },
};Code language: JavaScript (javascript)

You should set the environment variables DB_HOST, DB_PORT, DB_USERNAME, and DB_PASSWORD in the production.

Note that if you store the confidential information in the production.js file and commit it to a public repository, you’ll put the application’s security at risk.

The app.js will require the production.js or development.js, depending on the current Node.js environment:

let config;

const nodeEnv = process.env.NODE_ENV || "development";

if (nodeEnv === "devlopment") {
    config = require("./development.js");
} else {
    config = require("./production.js");
}

module.exports = config;Code language: JavaScript (javascript)

Fifth, load the configuration information from the app.js in the index.js file:

const config = require("./config/app.js");
console.log(config);Code language: JavaScript (javascript)

Using the environment variables to control which code to run

Sometimes, you may want to execute some code in the development environment but not in the production environment.

For example, you may want to show debugging information in the development environment but not in the production environment.

To do that, you can use the process.env to access the DEBUG environment variable. For example:

First, create a new module called debug.js and define a function that logs information only when the DEBUG is set:

module.exports = (data, level = "info") => {
    if (!process.env.DEBUG) return;

    switch (level) {
        case "info":
            console.info(data);
            break;
        case "error":
            console.error(data);
            break;
        case "warning":
            console.warn(data);
            break;
        default:
            console.log(data);
    }
};Code language: JavaScript (javascript)

Second, load the debug.js to the index.js file:

const debug = require("./debug");Code language: JavaScript (javascript)

Third, show some debug information to the console:

const debug = require("./debug");

debug("The app is starting....");Code language: JavaScript (javascript)

If you set the DEBUG environment variable to true, you’ll see the output.

Summary

• The process is a core module of Node.js. The process.env property holds all the environment variables.
• Store confidential information in the environment variables and use the process.env to access them.