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Node.js Express: API & CLI Apps

Command Line Interface (CLI) AppsCommand Line Interface (CLI) Apps

What Are CLI Applications?

Command Line Interface (CLI) applications are tools that allow users to communicate with software through command-line instructions. They offer speed, efficiency, and automation capabilities, making them ideal for various tasks.

Benefits of CLI Applications:

  • Quick Execution of Tasks: CLI apps are lightning-fast when it comes to task execution. You can accomplish tasks with just a few keystrokes;
  • Automation Potential: They are automation-friendly, enabling you to create scripts and automate repetitive tasks effortlessly;
  • Suitable for Server Environments: CLI apps are well-suited for server environments, where graphical interfaces may not be available or practical.

In previous chapters, you might recall encountering the terminal while running Node apps. It is that CLI we are talking about.

Understanding the process.argv

When you fire up a Node.js script (by typing node app) in the command line, the process.argv array becomes your trusty sidekick. It carries the arguments you provide along with the command. This array is like a treasure chest with:

  • Element 0: The path to the Node.js executable;
  • Element 1: The path to the script being executed;
  • Elements 2 and beyond: Any additional arguments provided by the user.

You've got the theory, and now it's time to witness it in action. Launch the same Node script on your local machine and witness the magic.

Have you ever wondered where Node.js resides on your computer? Now you can find out with a single line of code:

CLI App Example

The true power lies in how we wield these arguments in the scripts. Behold an example script that calculates the sum of numbers we provide as arguments:

Code Description
Line 1: Retrieves command-line arguments (excluding script name and Node.js executable path) and stores them in the args array.
Line 2: Calculates the sum of numbers in the args array using the reduce function. parseFloat converts each argument to a number. The initial value of the sum is set to 0.
Line 3: Outputs the calculated sum to the console along with the label "Sum:".

We're running the script and witnessing the magic unfold before our eyes.

Everything was clear?

Section 2. Chapter 5
course content

Course Content

Node.js Express: API & CLI Apps

1. Introduction

Backend Role in WebWhat is Node.js?Key Advantages of Node.js Installing Node.jsCreating Your First Node.js AppChallenge: First Node App"Introduction" Section Sum Up

2. Console Applications

OverviewWhat are Console Applications?Introduction to the FileSystemChallenge: FileSystemCommand Line Interface (CLI) AppsCommander ModuleReadline ModuleConsole App: Guessing GameWorking with DirectoriesConsole App: DirInspect Pro"Console Apps" Section Sum Up

3. Express.js Framework

OverviewRole of Express.js in Web DevelopmentHTTP RequestsSetting up an Express AppCreating RoutesTesting with PostmanMiddlewareBuilt-in MiddlewareCustom Middleware"Express.js Framework" Section Sum Up

4. Developing REST API

OverviewREST API Main ConceptsProject StructureSetting Up the Entry PointImplementing the "GET ALL POSTS" RouteImplementing the "GET POST BY ID" RouteImplementing the "CREATE POST" RouteImplementing the "UPDATE POST BY ID" RouteImplementing the "DELETE POST BY ID" RouteStarting and Testing the APIConclusion and Next Steps

Node.js Express: API & CLI Apps

Command Line Interface (CLI) AppsCommand Line Interface (CLI) Apps

What Are CLI Applications?

Command Line Interface (CLI) applications are tools that allow users to communicate with software through command-line instructions. They offer speed, efficiency, and automation capabilities, making them ideal for various tasks.

Benefits of CLI Applications:

  • Quick Execution of Tasks: CLI apps are lightning-fast when it comes to task execution. You can accomplish tasks with just a few keystrokes;
  • Automation Potential: They are automation-friendly, enabling you to create scripts and automate repetitive tasks effortlessly;
  • Suitable for Server Environments: CLI apps are well-suited for server environments, where graphical interfaces may not be available or practical.

In previous chapters, you might recall encountering the terminal while running Node apps. It is that CLI we are talking about.

Understanding the process.argv

When you fire up a Node.js script (by typing node app) in the command line, the process.argv array becomes your trusty sidekick. It carries the arguments you provide along with the command. This array is like a treasure chest with:

  • Element 0: The path to the Node.js executable;
  • Element 1: The path to the script being executed;
  • Elements 2 and beyond: Any additional arguments provided by the user.

You've got the theory, and now it's time to witness it in action. Launch the same Node script on your local machine and witness the magic.

Have you ever wondered where Node.js resides on your computer? Now you can find out with a single line of code:

CLI App Example

The true power lies in how we wield these arguments in the scripts. Behold an example script that calculates the sum of numbers we provide as arguments:

Code Description
Line 1: Retrieves command-line arguments (excluding script name and Node.js executable path) and stores them in the args array.
Line 2: Calculates the sum of numbers in the args array using the reduce function. parseFloat converts each argument to a number. The initial value of the sum is set to 0.
Line 3: Outputs the calculated sum to the console along with the label "Sum:".

We're running the script and witnessing the magic unfold before our eyes.

Everything was clear?

Section 2. Chapter 5
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