What is the Path Module in NodeJS? & What is Readline sync?

Path Module in NodeJS

By abstracting away variations in path standards among different operating systems, such as Windows, Linux, and macOS, the path module in Node.js offers tools for working with file and directory paths. You may manage paths with this module without worrying about file extensions, separators, or concatenations. You use const path = require('path') to include it in your files.

Resolving Absolute Paths and Manipulating Path Segments:

1. path.resolve(): The absolute path of a series of path segments can be determined using the path.resolve() method. It turns a series of paths or parts of paths into an absolute path. Path.resolve() will return the absolute path of the current working directory if no path segments are supplied. Resolve will utilize the first parameter as the base for the second if a second parameter is specified.
2. path.join(): This function mixes two or more path segments while automatically managing platform-specific separators.
3. path.normalize(): In order to provide a consistent format, the path.normalize() function, for example, resolves relative specifiers like. or.. and double slashes in file path strings.
4. path.dirname(): By extracting the directory portion of a path, the filename is eliminated.
5. path.basename(): The final part of a path, usually the filename, is returned by path.basename(). It is possible to exclude the file extension using an optional second parameter.
6. path.extname(): The function path.extname() yields the path’s extension (e.g., .txt, .js).
7. path.parse(): The function path.parse() converts a path string into an object by providing elements such as root, dir, base, name, and ext.

Additionally helpful is the __dirname global variable, which gives the name of the directory in which the script is now running. This information enables path creation with respect to the script. No matter which working directory the script is currently running from, this is useful when you need to refer to a file related to the script.

Querystring Module

URL query string parsing and formatting tools are available in the querystring module. In URLs, query strings often follow the? character, but they can also show up when working with POST data.

• querystring.parse(): In order to return a JavaScript object, the querystring.parse() method breaks down an existing URL query string into a collection of key-value pairs. Additionally, it can handle assignment characters and custom separators.
• querystring.stringify(): On the other hand, querystring.stringify() creates a query string from a map of key-value pairs (a JavaScript object). It takes assignment and custom separator parameters, just like parse.

Readline Module

An interface for reading data one line at a time from a Readable stream, such process.stdin, is offered by the readline module. Building interactive command-line interfaces (CLIs) is one application where this is especially helpful.

1. readline.createInterface(options): The readline module’s main function for getting started is readline.createInterface(options). An Interface instance is created, with the input stream (process.stdin for user input, or fs.createReadStream for a file) and output stream (process.stdout, for example) defined. Usually, you would set terminal to false for files.
2. Reading Data Line by Line (rl.on(‘line’)): Whenever a newline character (\r, \n, or \r\n) is received by the input stream, A line event is emitted by the Interface object. This enables line-by-line processing of input.
3. Prompting User Input (rl.question()): The question() method asks the user a question on the output stream and then watches the input stream for input. The entered string is passed to the callback function when the user hits Enter. It’s crucial to end the interface by calling rl.close() inside the callback.

Other events also supported by the readline module include pause (when the stream is halted), resume (when a stopped stream is restarted), and close (when the stream is closed). The underlying functionality of the readline module is also used by commands in the REPL (Read-Eval-Print-Loop), including .help, .editor, .break, .clear, .load, .save, and .exit also use the readline module’s allowing for interactive command-line experiences.

Providing strong and effective methods for managing file system interactions, parsing URL data, and developing interactive command-line tools, these utility modules are essential to Node.js development. They are made to easily connect with the asynchronous, event-driven architecture of Node.js, allowing programmers to create incredibly adaptable and powerful applications.

Readline sync

readline-sync is a popular Node.js module that lets you create synchronous command-line interfaces (CLIs). Essentially, it allows a Node.js program to pause and wait for user input from the console. This is different from the standard Node.js readline module, which is asynchronous and uses an event-driven approach.