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Node.js Express: API & CLI Apps

Console App: DirInspect ProConsole App: DirInspect Pro

This chapter presents you with a challenge: creating an advanced console app named DirInspect Pro. This app will empower you to thoroughly analyze any directory and gain insightful statistics about its files and subdirectories.

🏆 Challenge Awaits

Picture a scenario where you must navigate a labyrinth of folders containing crucial files and data. DirInspect Pro is your ally in this journey, providing comprehensive insights into the directory's structure and contents.

🚀 The Resulting App

Get ready to wield DirInspect Pro's capabilities. The app will furnish you with critical information, such as

  • The total number of items;
  • The aggregate size of all items;
  • The largest file's name and size;
  • The detailed list of individual file names and sizes.

App in Action

content

DirInspect Pro's Output:

content

Two Paths to Choose

You have two paths ahead.

  • The first is to tackle this challenge head-on, honing your skills without guidance;
  • The second is to follow a helpful guide that guarantees your success.

Whichever path you choose, you're in for a rewarding journey culminating in creating a captivating and functional console app.

Step 1: Import Required Modules

To embark on this adventure, you'll need the right tools. Begin by importing two key modules: fs.promises to manage the file system asynchronously and path to handle file paths effectively.

Code Description
Line 1: Imports the built-in fs module. The fs module provides functions for interacting with the file system in a Node.js environment. The .promises property is used here to access the promises-based API of the fs module, which allows asynchronous file operations to be written in a more modern and readable manner using async/await syntax.
Line 2: Imports the built-in path module. The path module provides utilities for working with file and directory paths. It's used to handle file path manipulation, normalization, and more.

Step 2: Define getStats Function

The asynchronous function, getStats, takes a file or directory path as an argument and attempts to retrieve its statistics using fs.stat.

  • If successful, it returns the statistics;
  • If an error occurs, it logs an error message and returns null.
Code Description
Line 1: This line declares an asynchronous function named getStats that takes a single parameter filePath.
Lines 2, 5: This structure is a try-catch block used for error handling. The code within the try block attempts to execute, and if any errors occur, they are caught and handled within the catch block.
Line 3: Inside the try block, this line uses the await keyword to asynchronously call the fs.stat(filePath) method. The fs.stat() method retrieves information about the specified file path, including details like size, creation time, and more. The await keyword ensures that the asynchronous operation is completed before moving on.
Line 4: If the fs.stat() operation is successful, the stats object containing file information is returned.
Line 6: If an error occurs during the fs.stat() operation, the catch block is executed. This line logs an error message along with the error's message to the console using console.error().
Line 7: If an error occurs, the function returns null to indicate that the file stats could not be retrieved successfully.

Step 3: Define analyzeFile Function

The analyzeFile function uses the getStats function to obtain statistics for a file. If statistics are available (not null), it returns an object containing the file's name (extracted using path.basename) and its size.

Code Description
Line 1: This line declares an asynchronous function named analyzeFile that takes a single parameter filePath.
Line 2: Inside the function, this line uses the await keyword to asynchronously call the getStats(filePath) function. This retrieves the file stats for the provided filePath.
Line 3: After obtaining the file stats, this line checks if stats is falsy (null, undefined, etc.). If it is, the function returns null immediately. This ensures that if there's an issue getting the stats, the function won't proceed further.
Line 5-8: If the file stats were successfully obtained and not null, this line constructs an object containing the file's name and size. It uses the path.basename(filePath) function to extract the filename from the full path and uses stats.size to include the file size in bytes.

Step 4: Define analyzeDirectory Function

The analyzeDirectory function takes a directory path as an argument and comprehensively analyzes its contents.

  • It begins by reading the items within the directory using fs.readdir and then iterates through each item;
  • For each item, it constructs the full path using path.join and retrieves its statistics using the getStats function;
  • If the stats indicate that the item is a file, it updates file-related statistics;
  • If the item is a subdirectory, it recursively calls the analyzeDirectory function to analyze its contents and then aggregates the statistics.
Code Description
Line 1: This line declares an asynchronous function named analyzeDirectory that takes a single parameter directoryPath.
Line 3: Inside the function, this line uses the await keyword to asynchronously call the fs.readdir(directoryPath) method. This retrieves an array of items (files and subdirectories) within the specified directory.
Lines 4-8: These lines declare variables to keep track of various statistics related to the directory and its contents.
Line 10: This for loop iterates over each item in the items array, which represents the contents of the directory.
Line 11: Inside the loop, this line constructs the full path to the current item by joining the directoryPath and item using path.join(). This is used to get the full path to each item within the directory.
Line 12: This line asynchronously retrieves file stats for the current item using the getStats function.
Line 13: If there's an issue getting the stats for the current item, this line skips to the next iteration of the loop using continue.
Lines 17-37: These conditional statements check if the current item is a file or a directory based on its stats.
    - If it's a file, statistics are updated: totalFiles and totalSize are incremented, the largest file is updated if necessary, and the file is added to the fileList.
    - If it's a directory, the analyzeDirectory function is called recursively for the subdirectory. The statistics of the subdirectory are then accumulated and merged with the current directory's statistics.
Lines 40-46: After analyzing all items within the directory, this line constructs and returns an object containing various statistics about the directory and its contents.
Lines 47-56: If any errors occur during the process of analyzing the directory, this catch block is executed. It logs an error message and returns default values for the statistics.

Step 5: Define main Function and Invoke

The main function is the entry point of the script. It specifies the directory path to analyze (in this case, ./docs), calls the analyzeDirectory function to obtain the statistics of the directory and its contents, and then outputs the collected information. The function prints out

  • The total number of items;
  • The total number of files;
  • The total size;
  • The details about the largest file;
  • The list of files in the directory.
Code Description
Line 1: This line declares an asynchronous function named main.
Line 2: This line defines the directoryPath variable, which holds the path to the directory that will be analyzed. In this case, it's set to "./docs", which is a relative path.
Line 3: This line calls the analyzeDirectory function with the provided directoryPath and uses the await keyword to asynchronously wait for the result. The result is stored in the directoryStats variable.
Lines 5-17: These lines use console.log() to display various information about the analyzed directory and its contents. It prints the total number of items, total number of files, total size in bytes, and details about the largest file.
Lines 18-20: This for loop iterates over each file object in the fileList array within the directoryStats object.
    - This line logs information about each file, including its name and size in bytes.
Line 23: Finally, this line calls the main function to start the analysis process.

🎉 Conclusion: Mastered Skills

With DirInspect Pro, you've mastered the art of analyzing directories like a pro. This console app showcases your ability to extract file statistics, handle errors seamlessly, and unveil meaningful insights about files and subdirectories within a specified directory.

👨‍💻 Full App Code

Everything was clear?

Section 2. Chapter 10
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

Console App: DirInspect ProConsole App: DirInspect Pro

This chapter presents you with a challenge: creating an advanced console app named DirInspect Pro. This app will empower you to thoroughly analyze any directory and gain insightful statistics about its files and subdirectories.

🏆 Challenge Awaits

Picture a scenario where you must navigate a labyrinth of folders containing crucial files and data. DirInspect Pro is your ally in this journey, providing comprehensive insights into the directory's structure and contents.

🚀 The Resulting App

Get ready to wield DirInspect Pro's capabilities. The app will furnish you with critical information, such as

  • The total number of items;
  • The aggregate size of all items;
  • The largest file's name and size;
  • The detailed list of individual file names and sizes.

App in Action

content

DirInspect Pro's Output:

content

Two Paths to Choose

You have two paths ahead.

  • The first is to tackle this challenge head-on, honing your skills without guidance;
  • The second is to follow a helpful guide that guarantees your success.

Whichever path you choose, you're in for a rewarding journey culminating in creating a captivating and functional console app.

Step 1: Import Required Modules

To embark on this adventure, you'll need the right tools. Begin by importing two key modules: fs.promises to manage the file system asynchronously and path to handle file paths effectively.

Code Description
Line 1: Imports the built-in fs module. The fs module provides functions for interacting with the file system in a Node.js environment. The .promises property is used here to access the promises-based API of the fs module, which allows asynchronous file operations to be written in a more modern and readable manner using async/await syntax.
Line 2: Imports the built-in path module. The path module provides utilities for working with file and directory paths. It's used to handle file path manipulation, normalization, and more.

Step 2: Define getStats Function

The asynchronous function, getStats, takes a file or directory path as an argument and attempts to retrieve its statistics using fs.stat.

  • If successful, it returns the statistics;
  • If an error occurs, it logs an error message and returns null.
Code Description
Line 1: This line declares an asynchronous function named getStats that takes a single parameter filePath.
Lines 2, 5: This structure is a try-catch block used for error handling. The code within the try block attempts to execute, and if any errors occur, they are caught and handled within the catch block.
Line 3: Inside the try block, this line uses the await keyword to asynchronously call the fs.stat(filePath) method. The fs.stat() method retrieves information about the specified file path, including details like size, creation time, and more. The await keyword ensures that the asynchronous operation is completed before moving on.
Line 4: If the fs.stat() operation is successful, the stats object containing file information is returned.
Line 6: If an error occurs during the fs.stat() operation, the catch block is executed. This line logs an error message along with the error's message to the console using console.error().
Line 7: If an error occurs, the function returns null to indicate that the file stats could not be retrieved successfully.

Step 3: Define analyzeFile Function

The analyzeFile function uses the getStats function to obtain statistics for a file. If statistics are available (not null), it returns an object containing the file's name (extracted using path.basename) and its size.

Code Description
Line 1: This line declares an asynchronous function named analyzeFile that takes a single parameter filePath.
Line 2: Inside the function, this line uses the await keyword to asynchronously call the getStats(filePath) function. This retrieves the file stats for the provided filePath.
Line 3: After obtaining the file stats, this line checks if stats is falsy (null, undefined, etc.). If it is, the function returns null immediately. This ensures that if there's an issue getting the stats, the function won't proceed further.
Line 5-8: If the file stats were successfully obtained and not null, this line constructs an object containing the file's name and size. It uses the path.basename(filePath) function to extract the filename from the full path and uses stats.size to include the file size in bytes.

Step 4: Define analyzeDirectory Function

The analyzeDirectory function takes a directory path as an argument and comprehensively analyzes its contents.

  • It begins by reading the items within the directory using fs.readdir and then iterates through each item;
  • For each item, it constructs the full path using path.join and retrieves its statistics using the getStats function;
  • If the stats indicate that the item is a file, it updates file-related statistics;
  • If the item is a subdirectory, it recursively calls the analyzeDirectory function to analyze its contents and then aggregates the statistics.
Code Description
Line 1: This line declares an asynchronous function named analyzeDirectory that takes a single parameter directoryPath.
Line 3: Inside the function, this line uses the await keyword to asynchronously call the fs.readdir(directoryPath) method. This retrieves an array of items (files and subdirectories) within the specified directory.
Lines 4-8: These lines declare variables to keep track of various statistics related to the directory and its contents.
Line 10: This for loop iterates over each item in the items array, which represents the contents of the directory.
Line 11: Inside the loop, this line constructs the full path to the current item by joining the directoryPath and item using path.join(). This is used to get the full path to each item within the directory.
Line 12: This line asynchronously retrieves file stats for the current item using the getStats function.
Line 13: If there's an issue getting the stats for the current item, this line skips to the next iteration of the loop using continue.
Lines 17-37: These conditional statements check if the current item is a file or a directory based on its stats.
    - If it's a file, statistics are updated: totalFiles and totalSize are incremented, the largest file is updated if necessary, and the file is added to the fileList.
    - If it's a directory, the analyzeDirectory function is called recursively for the subdirectory. The statistics of the subdirectory are then accumulated and merged with the current directory's statistics.
Lines 40-46: After analyzing all items within the directory, this line constructs and returns an object containing various statistics about the directory and its contents.
Lines 47-56: If any errors occur during the process of analyzing the directory, this catch block is executed. It logs an error message and returns default values for the statistics.

Step 5: Define main Function and Invoke

The main function is the entry point of the script. It specifies the directory path to analyze (in this case, ./docs), calls the analyzeDirectory function to obtain the statistics of the directory and its contents, and then outputs the collected information. The function prints out

  • The total number of items;
  • The total number of files;
  • The total size;
  • The details about the largest file;
  • The list of files in the directory.
Code Description
Line 1: This line declares an asynchronous function named main.
Line 2: This line defines the directoryPath variable, which holds the path to the directory that will be analyzed. In this case, it's set to "./docs", which is a relative path.
Line 3: This line calls the analyzeDirectory function with the provided directoryPath and uses the await keyword to asynchronously wait for the result. The result is stored in the directoryStats variable.
Lines 5-17: These lines use console.log() to display various information about the analyzed directory and its contents. It prints the total number of items, total number of files, total size in bytes, and details about the largest file.
Lines 18-20: This for loop iterates over each file object in the fileList array within the directoryStats object.
    - This line logs information about each file, including its name and size in bytes.
Line 23: Finally, this line calls the main function to start the analysis process.

🎉 Conclusion: Mastered Skills

With DirInspect Pro, you've mastered the art of analyzing directories like a pro. This console app showcases your ability to extract file statistics, handle errors seamlessly, and unveil meaningful insights about files and subdirectories within a specified directory.

👨‍💻 Full App Code

Everything was clear?

Section 2. Chapter 10
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