ode.js Features You Didn't Know About

Performance improvements and new features for Node.js: Competing with Deno and Bun

Many people are keen to discuss the speed of the new JavaScript runtime, which indirectly (and sometimes directly) implies that Node.js is slower or lacks certain integrated features. The development model of Deno 2 and Bun suggests that they are intended to be all-in-one toolkits for building JavaScript applications. They:

• Automatically load .env files
• Run the script in package.json
• Install package from npm
• Comes with built-in API for writing and running test suites
• Wait

Using Node.js requires the use of third-party tools to complete these tasks, such as using dotenv to load .env files.

However, Node.js has been catching up. This article will highlight three of the many features added since version 20 or 22. Let's get started.

Load .env file

Many people rely on dotenv to load environment files. We would write require('dotenv').config() or import 'dotenv/config' and then access the value from process.env. Starting in version 20.6.0, you can use the --env-file flag to specify the file from which Node.js should load environment variables.

For example, the following command will load environment variables from a .env file:

node --env-file=.env index.js

You can also load multiple files by passing the flag twice:

node --env-file=.env --env-file=config.env index.js

Some people have reported improvements in their application performance by removing the dotenv package and using Node.js directly. Here's what Wes Bos tweeted about his app startup time going from 1300ms to 1ms:

Monitor application files

I believe you have used different tools to monitor your source files and restart the application when you change the code. We have done this in various ways, one of which is using nodemon, a utility that monitors changes in source files and automatically restarts the server.

Starting with versions 18.11.0 and 16.19.0, the node CLI gets two new flags for doing this: --watch and --watch-path. Running node --watch index.js will start the application in watch mode and will watch the entry point and any required or imported modules. You should use the --watch-path flag to specify the paths to monitor, rather than entry files and their imported modules.

There is also a flag related to watch mode: the --watch-preserve-output flag. You can use this flag if you wish to prevent the console output from being cleared when the process is restarted in watch mode.

node --env-file=.env index.js

Run the script in package.json

While Node.js does not have a built-in package manager, most installations usually come bundled with npm. You've used npm run or similar commands from various package managers to run scripts defined in package.json . This isn't a problem, but Bun and Deno brag about the time it takes to get the package.json script up and running, which may have made the Node team reconsider this option.

Starting with version 22.0.0, Node.js can now run scripts via the --run flag, such as node --run dev. This doesn't just replace npm run without bringing any benefits or limitations. Using node --run has been proven to be faster than the npm run command. Some features intentionally excluded from other runtime implementations include:

• Run a pre-script or post-script in addition to the specified script.
• Define package manager specific environment variables.

You can read more about this flag in the documentation.

Summary

This article explores the latest improvements to Node.js that bring it closer to the integration capabilities provided by Deno 2 and Bun. We checked out the following features:

• Starting from version 20.6.0, use the --env-file flag to load .env files
• Local file monitoring capabilities provided by the --watch and --watch-path flags introduced in 18.11.0 and 16.19.0 versions
• The --run flag, available since version 22.0.0, provides a faster way to run package.json scripts

These updates help Node.js catch up with other runtimes by reducing the need for third-party tools and improving performance, security, and usability.

Original article published by me on Telerik blog

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