Modules are similar to Javascript libraries. It refers to the functions that need to be included in the application. Node.Js has numerous built-in modules that can be used without any installation. Express, Browserify, Moment.Js, JShint, and others are some of the most popular Node.js modules used widely across the world. Node.Js has approx 700K modules in-built which can be used whenever required. The modules in Node.js help the developers to use the readily available software to build applications instead of developing on their own. Trello, Uber, Paypal, and others are some of the well-known companies using Node. js to scale the efficiency of the organisation by leveraging the technology.

What is Node.js?

Node.js is an open-source and also cross-platform used to develop backend systems. It is widely used across the world in building applications that require a continuous connection between both the server and browser. The framework can also be used for building video streaming and real-time systems for chats. It was invented by Ryan Dahl. It is one of the strongest frameworks in the market as it can handle bulk requests and also respond easily one by one in no time. Node Option, NPM, Node report, ASYNC hook, and single-threaded model are a few of the features that make Node.js a preferred choice by many organisations across the world.

Node.js Modules

A Node.Js Module refers to the block of code that is encapsulated to communicate with applications that are external based on their functionality relationship. It can be either one file or can have multiple files or folders. Programmers prefer using modules because they can be reused and also broken down into manageable chunks from a piece of code that is complex. There are three types of Modules. Let us understand each one in detail.

Node.js Modules Types

1) Core Modules: As the name implies these modules are in built-in Node.js. They are included as a part of Node.Js platform and therefore come along with the installation of Node.js. The core modules are loaded using the syntax function. Depending on the particulars that a model returns the required function will then return a type of Javascript. There are many core modules in Node.js some of them are as follows:

• HTTP: In Nod.js, It is responsible for creating the HTTP server.
• Process: It provides control and also information about Node.js’ current process.
• Assert: As the name depicts these are a set of functions that are assertions and can be used for testing.
• Fs: It is used in handling the file system.
• Url: The Node.js module helps the users by providing utilities for URL parsing and resolution.
• Os: The operating system’s information is provided by it.
• Path: These include ways and methods of dealing with all the file paths.
• Querystring: To query URL strings query utility is used for formatting and parsing.

2) Local Module: As the name implies these modules are developed inside the application of Node.js. The module includes different functions of the applications in an independent folder or files. The user can also package and distribute these Via the Node Package Manager for the use of the Node.js community.
For instance: If the user wants to connect with MongoDB to fetch the data, create a module, and the same module can be reused again in the application.

3) Third-Party Modules: Third-party modules are the modules that are available to users online via the NPM (Node package manager). The user can install these modules either in the project folder or can also do it globally. Angular, React, Mongoose, and Express are some of the popular third-party modules. Npm installs express, npm install-g @angular/cli are some of the examples you can use the third-party modules.

How to create Node.js Modules

A node.js module is a package type which can be broadcasted to Node Package Manager. To create a Node.js module you need to follow the following steps

I) The first step is to build a package,json file.

II) Build the file that will be loaded when the other application requires your module.

III) The last step is to test the module.

I) Build package Jason file:

1. Run npminit to create the package Jason file in the root directory and also on the command line of the Node.js module.

• Run npminit..scope@scope-name for all the scoped modules.
• Run npm init for all the unscoped modules.

2. Need to respond to fields such as name, version, and also the main field.

• Name: The name of the module
• Version: This version of the module. Iit is recommended to start with 1.0.0 and follow the semantic version guidelines

II) Build the file which can be loaded when the other application requires your module:

Add a function in the file that resembles the property of exported objects. This will help in making the function accessible to all the other codes.

III) Test the Module:

Follow the below-mentioned steps to test the module

• Publish the package to the Node.JS package manager. For all the unscoped and private packages, you can use npm publish. For all the scoped public packages you npm publish access public can be used.
• Create a brand new directory for testing but outside the project directory on the command line.
• Now, switch to the directory created recently.
• Install the module inside the Test directory.
• Create a file known as test.js that requires the module and ensure that your module is now addressed as a method.
• Run node test.js on the command line. The message which was sent to the console.log should be displayed.

Node.js file system module

The Ndoe.js file system allows the user to work along the file system on their computer. Following are the types of file system modules
1. Read files: As the name implies the read files system allows users to read the files on the system. The function to be used is fs.readfile().
2. Create files: This file system has three methods to create new files.

• fs. appendfiles()
• fs. open()
• fs.writerfile()

The method fs.appendfile() appends the content which is specified to a file. If there is no file it will be created again.

The method fs.open() considers a flag as a secondary argument. If the flag for writing is “w” then the file which is specified is opened for writing. If this file also does not exist another file will be created which will be empty.
The last method replaces the content and the file which is specified only if the file exists. If not, a new file will be created with the content specified.

3. Update files: fs,appendfile() and fs.writefile() are the two methods for updating the files. The fs.appendfile() method appends the content which is specified toward the end of the file which is specified. The method fs.writefile() will replace the specified content and the files.
4. Delete files: Use the method fs.unlink() to delete a particular file in the file system module.
5. Rename files: Use the method fs.rename() to rename any file in the file system module.
6. Upload files: The user can use Node.JS itself to upload the files on the computer.

Node js URL module

The URL module in Node.js offers utilities for both parsing and URL resolution. The setters and also getters execute the properties of the URL objects on the class prototype and the class of URL is accessible on a global project. The New URL which is added in v7.0.0 & v6.13.10 is a method that is in the built application programming interface of the module that creates a fresh URL object in the base with the help of parsing the relative inputs.

How to test your module?

You can follow a few simple steps to test your modules.
1) The first step is to publish the package to the Node package manager.

• Use npm( Node package manager) to publish unscoped packages and private packages.
• Use npm to publish access public for scoped public packages.

2) The next step is to create a brand new directory for testing using the command line outside the project directory.

3) Now, switch to the directory which you have created recently.

4) You will have to then install the module in the new test directory.

5) Test. js file needs to be created in the new test directory that requires the module and calls it a method.

6) Run node test.js on the command line. The screen should display the message that was sent to console.log.

Important Node.js modules and their uses

The Node.js packages will help a developer to save time and resources. A developer will be able to develop applications easily also which are high-speed, light, and scalable with very high productivity. Let us understand the various packages of Node.js in detail

• Lodash: It is a Javascript library that helps users by providing utility functions. It is inspired by Underscore.js, a utility library. The functions built in Lodash make coding in Node.js easy. The user can just write a single line of code using Lodash rather than writing common functions multiple times.
• AsyncJS: Async also known as Asynchronous is used in the Node.Js to make sure that there is no blocking in the operation flow. It makes use of queues to monitor the workflow, permitting to include additional tasks, handling errors, and also attaching more callbacks. It also helps in avoiding memory leaks. Text strings and inline functions are also supported by AsyncJS
• Express: Express is one of the fastest and simplest frameworks of Node.js, it was created to help users build simple, multiple pages and also hybrid applications with powerful features for both mobile and web development.
• Moment.JS: It is a lightweight Javascript tool used for time and date manipulation. The user can easily manipulate date and time format, validate and also internationalize by using a concise API.
• JSHint: It is a static tool for analysis for Javascript. It is used to detect potential problems and errors in a code. It scans the Node.Js program and also reports common mistakes and all the potential bugs such as syntax errors, implicit type, leaking variables, and others.

Conclusion

Hope you have now understood the concept of Node.js modules. Knowing Node.js is not enough but knowing the modules will help to develop applications easily and also leverage the technology. Node.j is now the preferred choice of many organizations and startups across the world. As the demand for the technology is increasing so will the right talent for it. Explore all the career opportunities with HKR training today by visiting the centre. If you have any queries you can comment in the section below.