--description--

Client-Side JavaScript

• Client-Side JavaScript: Code that runs on the client side of a web application, usually in a web browser.
• Limitations of Client-Side JavaScript: While powerful, client-side JavaScript has certain limitations:
  • Very restricted access to local files.
  • Not designed for handling complex application logic.
  • Potential security concerns (e.g., exposing sensitive information like database credentials).
• Reason for Limitations: These limitations exist because client-side JavaScript was initially designed to run exclusively on web browsers.

Browser Environment

• JavaScript Engine: Web browsers provide the environment needed to run JavaScript code, including the JavaScript Engine.
• Document Object Model (DOM): Browsers provide access to the DOM, allowing you to access HTML elements in your code.
• Historical Context: Previously, JavaScript could not run outside of a browser, but now it can with Node.js.

What is Node.js?

• Node.js: A JavaScript runtime environment. Officially defined as "an open-source and cross-platform JavaScript runtime environment."
• Open Source: Node.js code is publicly available and maintained by a large community of developers.
• Cross-Platform: Works on any operating system, including Windows, macOS, and Linux.
• JavaScript Runtime Environment: Allows you to run JavaScript code outside of a browser.

Node.js Use Cases

• Common Applications: Node.js is used across a wide range of industries for:
  • Building web servers and APIs that handle HTTP requests.
  • Developing web and mobile applications.
  • Handling complex data and database interactions.
• Industry Adoption: If you are using or developing a website or web application that interacts with a database or handles complex data, there is a high chance that you will use Node.js behind the scenes.
• Key Characteristics: Node.js is efficient, scalable, and has a large community of developers and maintainers around the world.

Browser vs. Node Runtime Environment

• Browser Environment: Primarily designed for front-end web development, runs client-side JavaScript.
• Node Runtime Environment: Primarily designed for back-end web development, runs server-side JavaScript.
• API Differences: The environment determines the APIs available:
  • Browser: Access to the DOM API, but restrictions for accessing the local file system.
  • Node: Access to almost all system resources, including the file system, but not the DOM.

Global Objects

• Browser Global Object (window): Provides access to browser-related functionalities:

  • Methods for manipulating the DOM.
  • Managing cookies.
  • Handling browser events.

• Node.js Global Object (global): Provides access to Node.js specific functionalities:

  • Built-in modules for working with local files.
  • Networking capabilities.
  • Interacting with the operating system.

Version Control

• Browser Version: You have no control over the version of the browser environment that your users will use to visit your website.
• Node.js Version: You can choose the version of Node.js that you want to use in your server.

Importance of Node.js

• Full-Stack Development: Node.js has transformed web development by enabling developers to use JavaScript to build both the front-end and the back-end of full-stack applications.
• Efficiency: The development process is more efficient because developers don't need to learn a new programming language just for developing the back-end.
• Impact: Node.js is a powerful, scalable, and versatile tool that has become very important for developers worldwide.

Advantages of Node.js

• Single Language for Full-Stack: You can implement both the front-end and the back-end of a web application using JavaScript.

  • Reduces the initial learning curve.
  • No need to switch between programming languages.
  • Increases efficiency and productivity.

• Non-Blocking, Event-Driven Architecture: Great for developing real-time applications where responsiveness and efficiency are essential for creating a good user experience.

• Single Thread and Event Loop: Can effectively handle a large number of simultaneous requests and Input-Output operations.

  • Perfect for applications that require handling multiple requests simultaneously.

• Large Community: Thousands of developers around the world constantly maintain Node.js and add new features.

  • Many learning resources available.
  • Easy to find answers to questions.

• npm (Node Package Manager): A powerful tool that allows you to install and manage packages and modules for your projects.

  • Packages available for many purposes: handling HTTP requests, working with databases, formatting dates and times, testing code, and more.
  • Reuse code written, tested, and shared by other developers.
  • Makes workflow faster and more efficient.

• Cost-Effective: Node.js is free and open source.

  • Packages, libraries, and associated tools are also primarily free.
  • Important factor when optimizing budget.

Disadvantages of Node.js

• Single-Threaded Limitation: Only runs one thread at a time, meaning it can only handle one operation at a time.

  • While architecture allows efficient handling of concurrent (simultaneous) requests, CPU-intensive tasks may block the main thread and result in performance issues.
  • Examples of CPU-intensive tasks: complex mathematical operations, image and video processing, cryptography.
  • Ways to overcome this exist, but usually increase application complexity.

• Asynchronous Programming: Node.js relies on asynchronous programming.

  • A task that may take a long time to run is started, but instead of waiting until it's completed, the main program continues running while the asynchronous task runs in parallel.
  • When the task is completed, the program handles the result.
  • Often involves "callbacks," which are functions that define what happens when asynchronous operations are completed.
  • Can potentially make code more difficult to read, understand, and debug.

• Package Quality Concerns: When choosing packages from npm, some may not be constantly maintained and may introduce vulnerabilities into your application.

  • Developers should evaluate each package carefully.
  • Check if packages follow quality and security best practices.

Threads

• Thread: A path of execution within a process, like a computer program that is currently running.

NVM (Node Version Manager)

• NVM: A tool for managing multiple versions of Node.js on the same computer.
• Purpose: Helps you switch between different versions of Node.js for different projects easily.
• Recommendation: Installing NVM before Node.js is recommended for future flexibility.

Installing NVM on macOS/Linux

• Xcode Command Line Tools (macOS): Must be manually installed before running the NVM install script on macOS.

xcode-select --install

• Verify Xcode Installation:

xcode-select --version

• Download and Execute NVM Installation Script: Run one of these commands:

curl -o- https://raw.githubusercontent.com/nvm-sh/nvm/v0.40.3/install.sh | bash

wget -qO- https://raw.githubusercontent.com/nvm-sh/nvm/v0.40.3/install.sh | bash

• Terminal Restart: You might need to restart your terminal when the process is completed to load the new command and configuration.

• Verify NVM Installation:

nvm -v

Installing Node.js with NVM on macOS/Linux

• Install Latest LTS Version: To install the latest Long-Term Support (LTS) version of Node.js:

nvm install --lts

• LTS (Long-Term Support): This version is usually recommended because it prioritizes stability, reliability, and security over new or experimental features.

  • Thoroughly tested and ready for production.
  • Guaranteed to have longer support periods with a focus on bug fixes and security patches.

• Install Specific Version: You can install a specific version of Node.js by specifying the version number:

nvm install <version>

Example:

nvm install 20

• Switch to a Version:

nvm use <version>

Example:

nvm use 20

• Check Current Node.js Version:

node -v

Installing NVM on Windows

• Official NVM Support: Official versions of NVM only support Windows in specific cases.

  • If you have Windows Subsystem for Linux (WSL), you can follow the macOS/Linux guide above.

• nvm-windows: A Node.js version management utility for Windows.

  • Completely separate project from the official NVM project.
  • Same purpose: help you work with multiple versions of Node.js on the same device.

• Before Installing: It is recommended to uninstall any prior Node installation before installing NVM for Windows.

• Installation Steps:

  • Go to the Releases section of the official repository: https://github.com/coreybutler/nvm-windows/releases.
  • Download the latest installer.
  • Follow the instructions.

• Terminal Restart: You might need to restart your terminal if the nvm command is not immediately available.

• Verify Installation:

nvm -v

Installing Node.js using NVM for Windows

• Install Latest LTS Version:

nvm install lts

• Install Specific Version:

nvm install <version>

Example:

nvm install 20

• Switch to a Version:

nvm use <version>

Example:

nvm use 20

• Check Current Node.js Version:

node -v

Basic NVM and Node.js Commands

• Note on Commands: All commands work for NVM installed on macOS/Linux, including WSL. They may work differently or may not work at all for nvm-windows. Alternative commands for nvm-windows are provided when possible.

PowerShell Execution Policy (Windows)

• Default Execution Policy: PowerShell's default execution policy is Restricted, which prevents scripts from running as a security measure.

• Run PowerShell as Administrator: Right-click on PowerShell, then click "Run as Administrator".

• Check Current Execution Policy:

Get-ExecutionPolicy

• Set Execution Policy to RemoteSigned: Allows local scripts and npm to run:

Set-ExecutionPolicy RemoteSigned

• After Setting Policy: Close the administrator window of PowerShell and open a non-admin PowerShell window.

List All Installed Versions

• List Installed Versions: To list all installed versions of Node.js and check the one that is currently being used:

nvm ls

Set Default Node.js Version (NVM on macOS/Linux Only)

• Set Default Version: Sets the default version of Node.js for new terminal sessions:

nvm alias default <version>

Example:

nvm alias default 22.20.0

• Create Custom Aliases: Assign a more specific name to a version:

nvm alias <new_name> <version>

Example:

nvm alias new-api 18.20.8

• Use Custom Alias:

nvm use <new_name>

Example:

nvm use new-api

Remove a Version of Node.js

• Uninstall a Version:

nvm uninstall <version>

Example:

nvm uninstall 20.19.5

• Remove by Major Version (NVM on macOS/Linux): You can remove a version by running the uninstall command with a major version like 22 or 20:

nvm uninstall 20

If you have multiple releases for that major version installed, like 20.14.0 and 20.12.2, the latest version will be removed first. Running nvm uninstall 20 will remove 20.14.0 first.

Check Node.js Version

• Check Current Version:

node -v

Check npm Version

• npm: A package manager for Node.js used to install, publish, and manage software packages. Automatically installed when you install Node.js.

• Check npm Version:

npm -v

Run a JavaScript File

• Execute JavaScript File: Runs the JavaScript file in the currently active Node.js runtime:

node <file.js>

Example:

node app.js

Create a Node.js Project

• Initialize Project: Creates a new Node.js project by creating a package.json file that tracks its details and dependencies:

npm init

• Interactive Setup: The npm init command walks you through an interactive CLI guide for setting up the package.json file.

  • Asks questions for project name, description, version, etc.

• Default Setup: To start with a default package.json file:

npm init -y

or

npm init --yes

Install a Package

• Install Specific Package:

npm install <package>

Example:

npm install express

Install All Dependencies

• Install Dependencies: To install all dependencies listed in the package.json file of a project:

npm install

--assignment--

Review the Node JS introductory topics and concepts.