Node.js - What You Need to Know

What is Node.js?

Node.js is a platform which makes use of the Chrome V8 engine to enable JavaScript to be executed outside of an internet browser. Node.js is capable of being used on multiple Operating Systems, such as Windows, MAC, and Linux.

In a nutshell, Node.js enables you to use Javascript without a browser, thereby expanding the range of activities you can do online, like building a web server, developing a game, or accessing files on a server.

Using Node.js comes with a lot of advantages, some of which are:

It is open source and completely free.
You can write code for both frontend and backend.
Node.js is based on a non-blocking input/output(I/O) API —it doesn’t (have to) wait for the server to read a file. It sends the request to the server and continues with the next request.
It uses JavaScript on both the frontend and backend—no need to learn a new programming language. Take your JavaScript skills and start developing server-side applications.
It has pre packaged modules, usually called Node Modules , which makes using Node.js fast and fun.

Importance of debugging in Web Applications

Having a grasp of the right way to identify and address errors in software code can save lots of time invested in the engineering process. Troubleshooting does not only decrease the amount of time needed for development, but it also assists software creators in locating the spot of any mistakes and repairing them. When debugging, programmers can quickly pinpoint and remedy syntax mistakes and logical problems in their programs.

Debugging can also improve the quality of the application.

What is Node.js debugging?

Regardless of the complexity of your Node.js applications, you should anticipate encountering bugs. No software application is actually bug-free. The process of locating and correcting mistakes within your Node.js applications is known as Node.js debugging.

It is only the developer who determines which measures should be taken in order to debug a software application. However, there is a specific process that needs to be followed in order to debug effectively. The steps are:

Identify the bug. This can be done by QA, the developer, or even the end user.
Find the source of the bug.
Analyze the bug. Gain a deep understanding of the cause of the bug.
Find a solution for the bug.
Use your solution to fix the bug.
Test, test, and test.

Ways to debug in Node.js

In regards to troubleshooting Node.js projects, many coders depend on console.log and simply direct observations to the console. This solution appears to be adequate, but when diagnosing a complicated Node.js program, it is generally not the optimal way to proceed.

In order to troubleshoot your applications adequately, you will require a debugger- a program designed to go through the running of the code one line at a time, evaluate the values of any variables, and let developers know which lines of code was operated and why. When employing a debugger, you can inspect variables for mistakes or pinpoint where the value altered in the program.

When looking into tools to help troubleshoot your Node.js applications, there are several different debuggers you can choose from. Examples of popular development tools are Chrome DevTools, VSCode, Eclipse, and IntelliJ.

The inspect command is employed to launch the Node.js debugging process, making it feasible to attach any debugging application similar to Chrome DevTools. For example:

node inspect

To open Chrome DevTools to debug a Node.js application after starting the debugger with the inspect flag, go to the page chrome://inspect in a browser that is powered by Chromium.

To begin your project, click + Add Folder to the work area and provide the required permissions. Your project will appear on the left side.

To pause the running of code at a certain point, click the number associated with that line of code. The line is then marked blue.

To view the value of a specific variable when execution is halted, select the + symbol in the Watch pane and enter the name of the variable.

Utilize the buttons located on the left to pause, continue, walk through, or jump into your code, and to switch off breakpoints.

Key Features of Node.js

Different software architects have a range of explanations for why they select to utilize Node.js. We’ll explore its more important features below.

Event-driven and Asynchronous

All of the APIs in the Node.js collection are non-blocking or asynchronous. A server using Node.js will never have to wait for the API to give back information.

Speed

Node.js runs quickly due to its reliance on the Chrome V8 JavaScript Engine for code execution.

Single-Threaded With High Scalability

By saying that Node.js is single-threaded, we are referring to its utilization of a single-threaded design involving an event loop, enabling the program to handle more requests than a typical server would be able to. The Event mechanism helps the server with fast responses, allowing for greater scalability, in contrast to the constrained number of threads traditional servers offer for dealing with requests.

Take a moment to gain an improved comprehension of event looping by analyzing how the JavaScript Event Loop works. Place the main ( ) function onto the call stack, followed by the console.log ( ) function. This will run immediately, getting popped. Then push setTimeout (2000) onto the stack. This Node.js API will create a predetermined response when triggered by an event. The callback will happen following a 2,000 millisecond delay after the event.

Once the event is logged in the application programming interfaces, it is removed from its call stack after two thousand milliseconds. A setTimeout of 0 is registered in a similar way, implying that there are two Node.js application programming interfaces (APIs) that are ready to be executed. Using setTimeout (0) will cause the callback to go on the queue for execution after waiting for 0 seconds, as well as setTimeout (2000) which will delay the callback for 2000 seconds.

Once the functions have been transferred to the callback queue, they must wait until the call stack is empty since only one command can run at a given time. That occurs thanks to the event loop. Finally, the final console.log() will execute, while the main() is removed from its invocation stack. At this juncture, the event loop observes that the call stack is vacant, yet the callback queue has items in it. The callbacks are then transferred to the call stack in a first in, first out order, allowing them to be carried out.

Licensing

Node.js is open to the public under the MIT license, meaning that it is simple to obtain and utilize.

No Buffering

Node.js applications provide their data in segments, meaning you don’t ever have to manage buffering.

Understanding Node.js Files

When a Node.js file is built, there will be certain activities that are carried out when a certain occurrence takes place, such as someone making a try to gain access to a port on the server. Files with a .js extension, which are written in Node.js, must be started on a server to be used. If not, they will not have an effect.

Node.js Package Manager

npm, the Node.js package manager, is composed of community-made tools which can address the majority of standard issues that can arise. This tool is user friendly and has a selection of packages that can make development faster and more efficient.

Using Require

A necessary part of the process, require carries out a number of important duties, such as retrieving modules that are packaged with file systems like Node.js or HTTP from your API. The function takes in a “path” as an argument, and the outcome will be module.exports. It also brings in libraries that have been acquired from npms, and, as its name implies, it allows you to include your own documents and separate the project into modules.

Understanding Node.js Modules

Node.js modules are collections of code that can be utilized without bringing about any unintended effects on other code. The program is equipped with integrated components, and once you have some experience, you can construct them yourself to be employed in programs.

What You Can Do With Node.js

Node.js can be employed to generate interactive web page material and do the requisite procedures for managing files: production, commencement, analyzing, penmanship, disposing of, and shutting. It has the capability to acquire information from forms or modify, supplement, or delete information from a database.

Node.js is suitable for a variety of tasks, such as input/output related applications, data streaming applications, data-intensive real-time programs, single-page websites, and JSON-powered APIs, as well as chat and API applications with object-oriented databases. However, it is not ideal for CPU-intensive applications.

Node.js is a very reliable tool in the developer community, employed by some huge companies such as Uber, Wikipins, PayPal, Microsoft, GoDaddy, General Electric, Yammer and Yahoo!.

How to Write “Hello World”

Let’s utilize the traditional sample to construct the phrase “Hello World” with Node.js. Start by creating a file with a .js extension and add the following code:

console.log(“Hello World!”);

Now open up your Node.js terminal. Navigate to the folder, then switch it to whichever directory you saved the .js file to. Execute node __.js, replacing __ with the name of your file.

Common mistakes in Node.js

Errors are unavoidable in one’s everyday life, and when it comes to programming software, it is commonly (almost always) the programmer who is responsible for these mistakes. The vast majority of glitches found in software applications come about as the result of blunders made by the programmer or coders. Mistakes equal bugs. Avoid committing mistakes that are typical for developers utilising Node.js. Here are some of the most common mistakes and how to avoid them:

Blocking Event Loop

Node.js event loop is prevented from progressing when you have constructed code that needs to be completed before some other code starts running. As the Node.js documentation states, the event loop is unable to progress with any JavaScript tasks while a time-consuming operation is being carried out.

Typically, codes that impede event cycles are mainly synchronous (they stop all other directions until the job is finished). Take a look at the following code:

const fs = require("fs");
fs.readFileSync("my_file.png");
const content = "Hello world"

// This code(and every below) waits for the above code to finish executing before running
fs.writeFileSync('hello.txt', content)

// all other code waiting....

I read a picture from my computer files and then, contingent on the time it took to finish, put “hello world” in another document. It’s observable that the two codes do not depend on one another, yet the latter must pause until the former has been completed. Should the image file not be read successfully, the application will abruptly terminate.

In order to sidestep this issue, you have to code in an asynchronous manner. The following solution will fix the problem:

const fs = require("fs");
fs.readFile('/file.md', (err, data) => {
  if (err) throw err;
  
  console.log("file read....")
});

const content = "Hello world"

// This code dosent't have to wait for the above
fs.writeFileSync('hello.txt', content, err => {
  if (err) {
    console.error(err)
    return
  }
  //file written successfully
})

Both of our programs are executing simultaneously without either one waiting for the other. If one person does not fulfill their duties, it will not impede the progress of the rest.

Invoking callbacks more than once

When fs.writeFile() is through writing to the file test.txt, the callback function will produce the message “hey I’m done writing” in the console.

What do you believe is not functioning correctly with the code shown above? If you want to debug, take the code, paste it into your favorite Node.js code editor, create a test.txt document, run the program, and check the output.

The code shown is unable to open the file tes.text as it does not exist. Rather, we have a test.txt in our file system. But, you’ll notice that the callback happens twice. Even if a mistake is made, both will still be held accountable.

You may be questioning why my_callback() is being triggered twice now. That’s why the code continues to execute in Node.js even if the if (err) statement is present. We can keep executing the code all the way up to the final line.

The Else statement eliminates the necessity of using the return statement.

Any of these methods are suitable choices for eliminating these types of pests.

Deep nesting callbacks

Using callbacks can make it troublesome to keep up with and understand the code. Take a look at the following problem:

“I have 3 files. I need to transfer the data from the first file to the second file, carry out some computations, and then send the result to the final file.

Running synchronous callbacks

An issue with constructing callback functions is that they suspend the Event loop. An instance of this was demonstrated in the Blocking Event Loop area. A process that is asynchronous will remain on hold until the callback function has been executed before proceeding to execute the next line of code.