Package Manager

Introduction

A package manager or package-management system is a collection of software tools that automates the process of installing, upgrading, configuring, and removing computer programs for a computer in a consistent manner.

A package manager deals with packages, distributions of software and data in archive files. Packages contain metadata, such as the software's name, description of its purpose, version number, vendor, checksum (preferably a cryptographic hash function), and a list of dependencies necessary for the software to run properly. Upon installation, metadata is stored in a local package database. Package managers typically maintain a database of software dependencies and version information to prevent software mismatches and missing prerequisites. They work closely with software repositories, binary repository managers, and app stores.

Package managers are designed to eliminate the need for manual installs and updates. This can be particularly useful for large enterprises whose operating systems typically consist of hundreds or even tens of thousands of distinct software packages.

History

Early package managers, from around 1994, had no automatic dependency resolution but could already drastically simplify the process of adding and removing software from a running system.

By around 1995, beginning with CPAN, package managers began doing the work of downloading packages from a repository, automatically resolving its dependencies and installing them as needed, making it much easier to install, uninstall and update software from a system.

Purpose

A software package is an archive file containing a computer program as well as necessary metadata for its deployment. The computer program can be in source code that has to be compiled and built first. Package metadata includes package description, package version, and dependencies (other packages that need to be installed beforehand).

Package managers are charged with the task of finding, installing, maintaining or uninstalling software packages upon the user's command. Typical functions of a package management system include:

Working with file archivers to extract package archives.
Ensuring the integrity and authenticity of the package by verifying their checksums and digital certificates, respectively.
Looking up, downloading, installing, or updating existing software from a software repository or app store.
Grouping packages by function to reduce user confusion.
Managing dependencies to ensure a package is installed with all packages it requires, thus avoiding dependency hell.

NPM

Introduction

NPM basically, stands for Node Package Manager. It is a piece of code that is managed by the Package Manager.

NPM is the world's largest software registry. Open-source developers from every continent use npm to share and borrow packages and many organizations use npm to manage private development as well.

This package manager is used, for accessing or reusing someone else's open-source code managed by NPM by installing it into our project.

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Features

NPM is a package manager that manages the 3rd Party Open source code which we can use in our project.
Before using NPM modules, we need to initialize NPM locally using npm init on your command line in the root of your project folder.
Install any NPM package by using the command npm install <package name>
We can install the NPM package globally using the -g flag
Also, the package can be made development dependent using the --save-dev flag.

Basic Commands

To build projects using NPM, developers need to install Node js on their local computers.

Installation: To download the latest version of npm, on the command line, run the following command:

  npm install -g npm

  /* Now check your version of npm and Node.js */
  node -v
  npm -v

Dependencies: Now, to add a dependency for a project, suppose say express .
```
  npm install express --save
```
If you don’t specify the version, the latest one will be installed.

Once express is installed, the node_modules folder will be created with the same contents as an npm project.

Indeed you can see how package.json got updated without having to indicate Yarn to do it explicitly
```
  // package.json
  {
    "name": "npm-article",
    "version": "1.0.0",
    "main": "index.js",
    "license": "MIT",
    "dependencies": {
      "express": "^4.14.1"
    }
  }
```
Every time you execute NPM commands, npm_modules file will be updated automatically.

If you are using version control, it is important not to ignore this file. Instead, you have to put it on your repo and commit its changes.

The objective of npm_modules is to ensure that you are using the same versions of your dependencies no matter the environment like Netlify or Vercel.
npm_modules specifies the exact version of a package, not a range.

So even in package.json we have ranges.
```
  "dependencies": {
      "express": "^4.14.1"
    }
```
Dev dependencies: Package Managers allow you to specify dev dependencies too, for example for testing you might need mocha.

To install it you run
```
  npm install mocha --dev
```
Add package.json has a new section.
```
  "devDependencies": {
      "mocha": "^3.2.0"
   }
```
Remove dependencies: You can remove dependencies with uninstall command.

For example, to remove mocha just run
```
  npm uninstall mocha
```
This command will remove the package, and all of the packages it depends on, and update package.json and node modules.
Change versions: NPM allows you to change the versions of your packages, either if you want to update or install a previous version.

For example, to change express from 4.14.1 to 3.1.0, you run
```
  npm update express@3.1.0
```
After the command is executed, node modules is updated.

package.json is updated every time you add, upgrade or remove a package.
Installing all your modules: When you download an NPM project without its node_modules folder, to install all the modules you have to run
```
  npm install
```
With the information in package.json, NPM will install all the necessary modules.

To prove this, just remove node_modules of the current project and run the install command.
Global modules: If you want to install global modules, you can do it with global.

For example, if you want to add nodemon globally just run
```
  npm install nodemon -g
```
global is useful too to remove or upgrade global modules
```
  npm update nodemon -g
  npm uninstall nodemon -g
```

Yarn

Introduction

Yarn is a new package manager that is much faster, more reliable and more secure than npm. Facebook has used npm for developing products for a while, but once their products and teams started to grow, they experienced problems related to consistency, security and performance.

Instead of creating a solution for every new problem, they decided to tackle this problem with another approach.

Developed by Facebook in collaboration with Google, Exponent and Tilde, Yarn aims to enhance the development of products by removing the problems caused due to version incompatibility in modules used in the projects.

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Features

Much faster installation because every installed package is stored in a local cache.
Enhanced security to verify the integrity of every installed package.
Deterministic because the same dependencies will be installed in the same way no matter the environment.
More intuitive commands.

You can do all of this with 100% compatibility with npm, meaning you don't have to modify your source code in npm projects to switch to Yarn.

Basic Commands

Installation: To access Yarn from the terminal, you have to install it globally.

You can download or install using NPM,
```
  npm install -g yarn
```
Once the installation is done, we’ll create the folder for the intro folder
```
  mkdir intro
  cd intro
```
The process for creating a Yarn project is similar to npm and the command used is init
```
  yarn init
```
Dependencies: Now, to add express as a dependency with Yarn, we need to run
```
  yarn add express
```
You don’t have to specify --save and that’s because Yarn has better defaults.

By default, every dependency installed will update package.json.

If you prefer, you can install a specific version for a module with
```
  yarn add express@3.1.0
```
If you don’t specify the version, the latest one will be installed.

Once express is installed, the node_modules folder will be created with the same contents as an npm project.
Dev dependencies: Similarly, Yarn also allows you to specify dev dependencies too, for example for testing you need mocha.

To install it you run
```
  yarn add mocha --dev
```
And package.json has a new section
```
  "devDependencies": {
      "mocha": "^3.2.0"
   }
```
Remove dependencies: You can remove dependencies with remove command.

For example, to remove mocha just run
```
  yarn remove mocha
```
This command will remove the package, and all of the packages it depends on, and update package.json and yarn.lock.
Change Versions: Yarn allows you to change the versions of your packages, either if you want to upgrade or install a previous version.

For example, to change express from 4.14.1 to 3.1.0, you run
```
  yarn upgrade express@3.1.0
```
After the command is executed, yarn.lock is updated.

yarn.lock is updated every time you add, upgrade or remove a package.
Installing all your modules: When you download a Yarn project without its node_modules folder, to install all the modules you have to run
```
  yarn install
```
With the information in yarn.lock, Yarn will install all the necessary modules.

To prove this, just remove node_modules of the current project and run the install command. Yarn uses a local cache that makes it faster than npm.
Global Modules: If you want to install global modules, you can do it with global.

For example, if you want to add nodemon globally just run
```
  yarn global add nodemon
```
global is useful too to remove or upgrade global modules
```
  yarn global upgrade nodemon
  yarn global remove nodemon
```

Conclusion

I hope you find this article useful and be able to start using NPM & Yarn in your projects to enhance your workflow. To be precise, Yarn offers a lot of new and enhanced features, but it's totally on you or your project what it needs for development.

Thanks for reading. And happy coding!

Guide to NPM and Yarn

This article is going to be a simple and beginners perspective on package managers, helpings everyone to learn about the technology.

Table of contents

Package Manager

Introduction

History

Purpose

NPM

Introduction

Features

Basic Commands

Yarn

Introduction

Features

Basic Commands

Conclusion

Guide to NPM and Yarn

This article is going to be a simple and beginners perspective on package managers, helpings everyone to learn about the technology.

Table of contents

Package Manager

Introduction

History

Purpose

NPM

Introduction

Features

Basic Commands

Yarn

Introduction

Features

Basic Commands

Conclusion

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