Node.js basics

Description

This project demonstrates the completion of several tasks on Node.js basics.

The project was completed as part of the RS School NodeJS 2024 Q3 course.

The project contains several nested folders inside src, with the necessary functionality implemented within them. The output results are displayed in the terminal, with highlights in color and formatted for easy readability.

During the testing and execution of functions, the content of the project changes; some files are renamed, deleted, or their content is modified. A script has been added to the project to restore it to its original state.

Technical requirements

• Use 22.x.x version (22.9.0 or upper) of Node.js.
• For convenient function execution, npm-scripts are defined in package.json to run each subtask.
• To return the project to its original state, run the restore.js script.

Subtasks

File system (src/fs)

Implemented several functions in dedicated files:

• create.js - Function that creates a new file fresh.txt with content I am fresh and young inside the files folder. If the file already exists, an Error with the message FS operation failed is thrown.
• copy.js - Function that copies the files folder with all its content into the files_copy folder at the same level. If the files folder doesn't exist or files_copy has already been created, an Error with the message FS operation failed is thrown.
• rename.js - Function that renames the file wrongFilename.txt to properFilename.md. If there's no file wrongFilename.txt or properFilename.md already exists, an Error with the message FS operation failed is thrown.
• delete.js - Function that deletes the file fileToRemove.txt. If there's no file fileToRemove.txt, an Error with the message FS operation failed is thrown.
• list.js - Function that prints an array of filenames from the files folder into the console. If the files folder doesn't exist, an Error with the message FS operation failed is thrown.
• read.js - Function that prints the content of the fileToRead.txt into the console. If there's no file fileToRead.txt, an Error with the message FS operation failed is thrown.

Command line interface (src/cli)

Implemented several functions in dedicated files:

• env.js - Function that parses environment variables with the prefix RSS_ and prints them to the console in the format RSS_name1=value1; RSS_name2=value2.
• args.js - Function that parses command line arguments (given in the format --propName value --prop2Name value2) and prints them to the console in the format propName is value, prop2Name is value2.

Modules (src/modules)

Refactored file cjsToEsm.cjs and renamed to esm.mjs:

• esm.mjs - Rewritten to its equivalent of cjsToEsm.cjs in ECMAScript notation.

Hash (src/hash)

Implemented several functions in dedicated files:

• calcHash.js - Function that calculates the SHA256 hash for the file fileToCalculateHashFor.txt and logs it into the console as hex using the Streams API.

Streams (src/streams)

Implemented several functions in dedicated files:

• read.js - Function that reads the content of the file fileToRead.txt using a Readable Stream and prints its content into process.stdout.
• write.js - Function that writes process.stdin data into the file fileToWrite.txt using a Writable Stream.
• transform.js - Function that reads data from process.stdin, reverses the text using a Transform Stream, and then writes it into process.stdout.

Zlib (src/zip)

Implemented several functions in dedicated files:

• compress.js - Function that compresses the file fileToCompress.txt to archive.gz using zlib and the Streams API.
• decompress.js - Function that decompresses archive.gz back to fileToCompress.txt with the same content as before compression using zlib and the Streams API.

Worker Threads (src/wt)

Implemented several functions in dedicated files:

• worker.js - Extended the given function to work with data received from the main thread and implemented a function that sends the result of the computation to the main thread.
• main.js - Function that creates a number of worker threads (equal to the number of host machine logical CPU cores) from the file worker.js and is able to send data to those threads and receive the result of the computation from them. Incremental numbers starting from 10 are sent to each worker. For example, on a host machine with 4 cores, 4 workers are created and 10 is sent to the first worker, 11 to the second worker, 12 to the third worker, and 13 to the fourth worker. After all workers finish, the function logs an array of results into the console. The results are an array of objects with 2 properties:
  • status - 'resolved' in case of successfully received value from worker or 'error' in case of error in worker.
  • data - value from worker in case of success or null in case of error in the worker.

The results in the array are in the same order that the workers were created.

Child Processes (src/cp)

Implemented several functions in dedicated files:

• cp.js - Function spawnChildProcess that receives an array of arguments args and creates a child process from the file script.js, passing these args to it. This function creates an IPC-channel between stdin and stdout of the master process and the child process:
  • The child process stdin receives input from the master process stdin.
  • The child process stdout sends data to the master process stdout.