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 is named package.json, this will contain the list of packages that we will use in json data format, the source code always wei be stored in a folder called node_modules. Creating this file is easy just by typing the command.
When we push new code to the repository of our project, usually the we do not save the files from node_modules folder there, we only add main file package.json. In case we want to install the project to another computer we just cloning the repository and then reinstalling packages by typing in cli the following.
Some of the popular packages of npm is 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 are newer version we do it using the command, this check the versions from package.json file against the online registry of the package manager
After that we can update all modules but this 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 express
What is Yarn
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 do an installation through 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 updated software and from package.json, to create one type
for installing packages
The last years npm overcome previous problem so npm and yarn are almost the same, so it's matter of preference.
Installing Tensorflow for machine learning
yarn add @tensorflow/tfjs
yarn add @tensorflow/tfjs
Setting up environment for ML is easy, now if we to use predefined deep learning models to implement directly data from to a web application, using keras. A detailed guide to import python keras models in Tensorflow.js there is the official website.