Nowadays every programming language has one or more package managers, let's explain this. It's a command-line tool that allows us to add software packages to a project, that is public and high quality. Also, we can track versions of packages and install all necessary dependencies. Programming languages such as PHP has composer, Rust has cargo and for nodejs and vanilla javascript 2 populars are npm and yarn.

What is NPM

Npm is the default package manager for nodejs, we can search and browse available packages in the official website npmjs.com. When we use npm in a project first we have to create an important file that named package.json. This will contain the list of packages that we will use in JSON data format, the source code always will be stored in a folder called node_modules. Creating this file is easy just by typing the command.

npm init

When we push new code to git repository of our project, a good pracrice is not save the files from node_modules folder. So add this .gitignore file node_dules and we only update the main file package.json. In case we want to install the project to another computer we cloning the repository and then reinstalling packages by typing in cli the following.

npm install

Some popular packages of npm are the express a web framework for nodejs, another is the React Native from facebook which is a tool for building native mobile applications.

For checking if some of the modules are old and there is the newer version we do it using the command, this check the versions from package.json file against the online registry of the package manager

npm outdated

After that, we can update all modules but it's best to do it only when we properly have setup software testing procedures. Also, we can make individual updates per package by using their name e.g. for express package

npm update
npm update express

What is Yarn

The first few years after npm was created there were many setbacks and bottlenecks like low security, not deterministic installation and slow download and installation speed for packages. So facebook created Yarn as an alternative package manager for nodejs to overcome all these problems.

When you make an installation using yarn for a new package the exact version and related dependencies and metadata are saved to lock file yarn.lock . After 2018 npm also improved and add support of auto-generation of a lock file, so now can support deterministic installation, the lock file is named package-lock.json.

The official site is yarnpkg.com and  the logic is the same for installing and updating software and from package.json, to create one type

yarn init

for installing packages

yarn

The period npm overcome the previous problem so npm and yarn are almost the same, so it's a matter of preference.

Installing Tensorflow for machine learning

As mentioned before, package managers can simplify the use of external resources like libraries and APIs. Here an example, let's install the javascript library for Tensorflow. It is an ML library, that you can use it in a custom web-based project, installation is easy with the following command.

npm:

yarn add @tensorflow/tfjs

yarn:

yarn add @tensorflow/tfjs

So now we can easily build and train machine learning models using a purely javascript library directly in any browser. Also, there are other versions of tensorflow if you want to be run as a backend in the server-side through nodejs.

Setting up Machine Learning is easy, if we want using predefined deep learning models for web applications, using Keras. A detailed guide to import python keras models in Tensorflow.js there is the official website.

package manager self-update

As we previously mention using a package manager make easy to download, install and update packages, but the same package manager have to be upgraded so first we have to check the version

npm -v

upgrade to the latest version

npm install -g npm@latest

Conclusion

Package managers automating the installing and upgrading of software, npm and yarn almost have the same level in security and performance at this time, so for web developer there are no such big differences anymore who knows javascript ES6 features. Even building a mobile application or progressive web applications could be done easily using reactjs and firebase and firestore just by installing everything with these package managers.