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Adding and Removing Packages with npm and Yarn

Adding and Removing Packages with npm and Yarn
Hostman Team
Technical writer
Node.js
27.04.2024
Reading time: 4 min

One of the main benefits of open sourced code is that most standard modules in modern programming languages have already been written, often in several different implementations. They were tested by dozens or even hundreds of programmers. The developer only needs to find and adapt the code to their own application. This significantly speeds up development, reduces the risk of errors, and allows you to release new products quickly.

The above is also true for the Node.js software platform. It is based on the V8 engine and turns JavaScript from a highly specialized tool into a general-purpose language. Various packages have been developed on it, mainly for web applications, such as chats, communication applications, and gaming programs. 

In this article, we will look at the Node.js yarn and npm utilities used for managing packages in the Node.js environment. They both access the package.json manifest file and function in a similar way. 

Prerequisites

To follow this guide, you will need:

  • A server or a computer with Node.js installed. 

On Hostman, you can deploy a cloud server with pre-installed Node.js in a few seconds. 

You don’t have to install npm and yarn separately as they will be installed on your machine with Node.js.

Creating a project

In this article, we will be installing dependencies for a particular project as well as globally. 

If you already have a project, you can use it, or you can create a new project for testing purposes, for example, in the /tmp directory:

mkdir/tmp/mynewproject
cd /tmp/mynewproject
npm init -y

The above commands will create a package.json file, from which we will add or remove packages.

Installing development dependencies

Some dependencies might be needed only at the development stage, and then they can be freely deleted. 

Typical development dependencies are testing programs like mocha or jest. You can install them with the commands:

NPM

npm install --save-dev mocha

# Or:

npm i -D mocha

Yarn

yarn add --dev mocha

# Or:

yarn add -D mocha

This will add the dependencies to the devDependencies section of the package.json file.

Installing production dependencies to a project

If a dependency is critical to the functioning of the application, it must be installed regardless of the stage, be it development or production. This category includes packages like express, react, on which the file structure, API support, user interface etc depend. 

The commands to install them are similar; however, they will be added to the dependencies section of the package.json file.

NPM

npm install --save express

# Or:

npm i -P express

Yarn

yarn add express

Installing dependencies globally

The development of similar applications makes it more convenient to install the required packages globally, so they are available for all your projects. 

This is how to install global dependencies in Node.js with npm and yarn.

NPM

npm install --global json

# Or:

npm i -g json

Yarn

yarn global add json

Removing dependencies from a project

At some point, you will need to remove a package or a few when they are no longer necessary for your project. It applies to both development and production dependencies. 

To remove dependencies from a project, use:

NPM

npm uninstall jest

# Or:

npm r jest

Yarn

yarn remove jest

The command will remove packages from node_modules and remove the dependency from package.json.

Removing dependencies globally

The same applies to global dependencies. If you completed a bunch of similar projects, there might be a few dependencies that are no longer needed. The removal procedure is similar to the previous example, but the --global option is used here, as when installing dependencies globally:

Example command:

NPM

npm uninstall --global json

# Or:

npm r -g json

Yarn

yarn global remove json

Conclusion

We described how to use npm and yarn in Node.js for managing packages, adding and removing dependencies used when developing applications on Node.js. 

The npm and yarn package managers complement the basic functionality and allow you to speed up the creation of programs on both the front-end and back-end sides.

Node.js
27.04.2024
Reading time: 4 min

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02 May 2025 · 6 min to read
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Using node-cron to Automate Tasks in Node.js

In many projects, there is a need to automate the execution of functions or scripts at specific times. To address this need in Node.js, you can use the node-cron library. In this article, we’ll cover how to install the package, explore best practices, build a simple project, and deploy it to the cloud. What Are Cron and node-cron? Cron is a task scheduler used in Unix-like operating systems (such as Linux) that allows you to automatically run commands or scripts on a schedule. The schedule is written in crontab format, where each line describes the time and command to be executed. node-cron is a library for Node.js that implements cron functionality directly in JavaScript applications. It allows you to create tasks that run on a given schedule in real-time in a selected time zone, just like classic cron in Unix systems. 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Testing the Project To run your project, execute: node index.js You will see this message in the console: Data collection started... And a little later you’ll see logs like: Rate saved: 4/9/2025, 12:00:00 PM - 0.92 EUR And the exchange_rates.txt file will contain entries with the date, time, and exchange rate. Using node-cron in a Real Project Let’s apply node-cron in a practical task. We’ll write a script that automatically sends emails. Companies often use this case to send various promotional content. It’s simple to implement but quite functional. Getting an App Password First, we need to obtain a token for your Gmail account: Log in to your Google Account. Go to the Security section. Enable Two-Step Verification. You'll be asked to confirm your identity, for example, via a code sent by SMS. Once enabled, proceed to the next step. Go to App Passwords to generate a new app password. Give your app a name (e.g., "nodemailer") and create it. A modal window will appear with the password. Copy this password and use it in your code. Writing the Code First, install the required libraries. Since node-cron is already installed, we only need to install nodemailer: npm install nodemailer Now create a file called app.js and write the following code: const nodemailer = require('nodemailer'); const cron = require('node-cron'); const recipients = [ 'recipient1@gmail.com', 'recipient2@outlook.com' ]; let transporter = nodemailer.createTransport({ service: 'gmail', auth: { user: 'sender@example.com', pass: 'PASSWORD' } }); function sendEmail(recipient) { let mailOptions = { to: recipient, subject: 'Scheduled Email', text: 'This email was sent automatically on a schedule using node-cron.', html: '<b>This email was sent automatically on a schedule using node-cron.</b>' }; transporter.sendMail(mailOptions, function(error, info){ if (error) { console.log(`Error sending email to ${recipient}:`, error); } else { console.log(`Email successfully sent to ${recipient}:`, info.response); } }); } cron.schedule('* * * * *', () => { console.log('Running cron job...'); recipients.forEach((recipient) => { sendEmail(recipient); }); }); Explanation: The recipients array contains the list of email recipients. The transporter variable holds the authentication info for the sender. Replace user with your Gmail address and pass with the generated app password. sendEmail() is a function that takes a recipient's address and sends an email. mailOptions holds the subject, plain text, and HTML content. The cron.schedule('* * * * *') task runs every minute, calling sendEmail() for each recipient. Testing the Application To run the file, use the command: node app.js After a couple of minutes, you’ll see output in the console confirming the emails have been sent. Check your inbox, and you should see the emails arriving. Deploying the Project on a Cloud Server (Hostman) After development, we’ll deploy the app to the cloud. For this lightweight mailer, a minimal server setup is sufficient. 1. Install Node.js on your server: curl -o- https://raw.githubusercontent.com/nvm-sh/nvm/v0.40.1/install.sh | bash \. "$HOME/.nvm/nvm.sh" nvm install 22 Check the installation: node -v && npm -v 2. Create the project directory: cd /home && mkdir nodemailer 3. Upload your files (app.js and package.json) On Windows, use FileZilla. On Linux/macOS, use: rsync -av --exclude="node_modules" ./ root@166.1.227.189:/home/nodemailer Explanation: --exclude="node_modules" — skip uploading installed libraries ./ — source directory root@166.1.227.189:/home/nodemailer — target path on the server 4. SSH into the server and verify the files: cd /home/nodemailer && ls 5. Install dependencies: npm install 6. Run the script: node app.js Check if the emails are being sent correctly. If there’s an issue, make sure port 465 (SMTP) is open on the server. If not, contact support to open it. To keep the app running even after closing the terminal, create a systemd unit file: sudo nano /etc/systemd/system/nodemailer.service Paste the following content: [Unit] Description=NodeMailer Service After=network.target [Service] User=root WorkingDirectory=/home/nodemailer ExecStart=/root/.nvm/versions/node/v22.14.0/bin/node /home/nodemailer/app.js Restart=always RestartSec=5 [Install] WantedBy=multi-user.target Note: Adjust WorkingDirectory and ExecStart paths if necessary. Enable and start the service: sudo systemctl daemon-reload sudo systemctl enable nodemailer.service sudo systemctl start nodemailer.service Check status and logs: sudo systemctl status nodemailer.service sudo journalctl -u nodemailer.service -f You should see active (running) if everything is working properly. Service Management Commands Restart the service: sudo systemctl restart nodemailer.service Stop the service: sudo systemctl stop nodemailer.service Delete the service: sudo systemctl disable nodemailer.service sudo rm /etc/systemd/system/nodemailer.service sudo systemctl daemon-reload Conclusion The node-cron library is a powerful tool for automating tasks on the Node.js platform. In this article, we created a simple app that retrieves USD to EUR exchange rates and writes them to a file, and we also explored a real-world use case: automatically sending scheduled emails. We’ve seen how easily node-cron enables you to schedule recurring jobs, from data collection to user interactions. It’s a great choice for developers looking for a reliable and user-friendly scheduling system in Node.js projects. Its flexibility and ease of use make node-cron an essential tool in any modern backend developer’s toolkit.
15 April 2025 · 10 min to read
Node.js

How to Install and Use Yarn Package Manager for Node.js

Yarn is an efficient tool for managing dependencies in Node.js-based projects. It is known for its high speed, security, and ease of use. What is Yarn and Why Use It? Yarn is an alternative to the standard npm (Node Package Manager). It is designed to handle packages and projects built on Node.js. Yarn offers several advantages over npm: Speed: Yarn downloads packages in parallel, significantly reducing installation time. Security: The use of a yarn.lock file helps prevent version conflicts. Deterministic Builds: Ensures identical package versions across different machines. User-Friendly Interface: Cleaner command syntax and additional tools for dependency management. If your project involves working with many packages and dependencies, using Yarn can greatly simplify the task. It allows for faster and more secure package installations while making dependency management more predictable — a valuable benefit for team-based projects. Comparison of Yarn and npm Yarn's advantages make it particularly appealing for developers, especially in large-scale projects. Feature Yarn npm Installation Speed Faster thanks to caching Slower Dependency Handling Deterministic builds Potential version conflicts Lock File yarn.lock package-lock.json Ease of Use Simplified syntax More standard interface Installing Yarn Before installing Yarn, ensure that Node.js and npm are installed: Open the terminal or command prompt. Run the following commands to check the versions of Node.js and npm: node -vnpm -v If Node.js or npm is not installed, download them from the official Node.js website. You may also find our installation guide helpful. To install Yarn globally, run: npm install -g yarn Check if Yarn was installed successfully: yarn --version If the command returns the version number, Yarn has been installed correctly. Yarn Commands Yarn's intuitive syntax makes it easy to manage your project dependencies efficiently. Project Initialization To get started with Yarn, initialize your project to create a package.json file containing project and dependency information. Navigate to your project directory: cd your-project-directory Run the following command and follow the prompts: yarn init This will generate a package.json file with basic project settings. Installing Packages To install a single package: yarn add <package-name> This adds the specified package to your project. To install a package as a development dependency: yarn add <package-name> --dev This is useful for packages required only during development. To install a specific version of a package: yarn add <package-name>@<version> This allows you to select the desired package version. Installing All Dependencies If the project already contains a package.json or yarn.lock, run: yarn install This is helpful when cloning a project from a repository to quickly set up the environment. Removing Packages To remove a package from your project and update package.json, use: yarn remove <package-name> Updating Dependencies To upgrade packages to their latest versions, run: yarn upgrade This ensures your project uses the most current versions. Dependency Security Audit To identify vulnerabilities in your project dependencies: yarn audit This helps detect and address potential security threats. Caching Yarn leverages caching to speed up subsequent package installations. To clear the cache: yarn cache clean This command can be useful if you encounter issues during package installation. Conclusion Yarn is a modern tool for managing dependencies in Node.js projects. Its speed, security features, and intuitive interface make it an excellent choice for developers.
10 February 2025 · 3 min to read

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