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Nodejs is a server-side technology and is one of the most popular ones among MEAN stack developers. It is quite rewarding and popular tool that can be learned by them and this is highly in-demand by the organizations. Node.js developers are offered lucrative salaries that are around $100,000 per year. If you are also planning to shape your career as a Mean stack developer then this article will surely help you in shaping your career growth. Here, we will discuss commonly asked Node JS interview questions and answer for the mean stack developer profile.
If you want to apply as a Node.js developer then it is good to learn the basic concepts and get familiar with the language. This post will cover the questions that are mostly asked by the interviewers. The questions covered in this article will surely help you in answering most of the questions asked by the interviewer with full confidence. Moreover, here we have covered all common questions of Noed.js that are collected by the experts for fresher and experienced candidates. Both can read and practice these questions before going for an interview.
Node.js is a server-side scripting technology that is based on JavaScript engine of Google’s V8. It is used to build scalable web application programs that are quite simple but frequently needed for application development.
I/O intensive web applications like video streaming of websites can be done through Node.js Real-time web applications can also be developed through Node.js, not only this even network applications, distributed systems, and general-purpose applications can be developed by Node.js
Scalable network programs can be developed easily by Node.js and if you like to know that why we should use Node, js then due to below-listed advantages it is usually used by the organizations:
Node.js is highly scalable and single threaded system that utilizes JavaScript as the scripting language. Rather than using separate threads or processes, it uses event-driven and asynchronous I/O. High output can also be achieved just be single threaded event loop and by its non-blocking I/O.
Following command is used to update NPM to a new version:
$ sudo npm install npm –g/usr/bin/npm -> /usr/lib/node_modules/npm/bin/npm-cli.js
npm@2.7.1/usr/lib/node_modules/npm
For asynchronous processing, Node.js is single threaded technology especially for managing typical web loads, scalability, and performance. Unlike typical thread-based applications, these applications are highly optimized and have better features.
Call back is a Node.js function that is called when any task is completed. This function is used to avoid blocking and allows other function to run. Due to asynchronous feature, Node.js use callback function extensively. Node APIs are written to support callbacks of Node JS.
REPL or Read Eval Print Loop are the tasks as per their names like for reading, evaluation, printing, and looping. Ad-hoc JavaScript statements are executed through REPL. It allows direct entry to the JavaScript shell prompt and the result also gets evaluated. REPL is important for testing, debugging, and experimenting.
NPM is Node package manager that provides below-listed two functionalities:
Ajax is asynchronous javascript and XML and is the advance implementation of JavaScript just like Node, js. They both serve purely different purposes.
Ajax is defined and designed to update a particular section of a web page, in which user need not to update complete web page and a page section is usually updated dynamically in Ajax technology. Node.js is basically used to develop apps based on client-server architecture.
When the output of one stream gets connected to another stream as input to create a chain of multiple operations then it is called chaining. It is just a mechanism to define multiple operations.
In Node.js stream allow users to read data from source and o write data to a destination in a continuous process. They are just an object and following four types of streams are there in Node.js they are:
Exit codes are used to end a specific process in Node.js and are some specific codes. The processes can be any global object as well. Some of the exit codes are listed below:
Globals is a group of keywords in Node JS. Below-listed keywords usually lie under this category:
Angular JS framework is used for web application development while Node.js is just a runtime system that is used to develop client-server applications.
Without adopting a new style, the team members of any project can modify a project easily. For this style generally, Standard and ESLint tools are used.f
A result of heavy callback nesting is known as callback hell, it makes the code highly unreadable and difficult to maintain. Like in the below listed example:
Query(“”SELECT employeeid FROM employee WHERE employeename=’Ankit’;”, function(id){ query(SELECT * FROM accounts WHERE employeeid=” + id, function(salary){ salary.each(function(sal){ query(“UPDATE salary SET value=”+(sal.value*0.1)+” WHERE id=” +sal.id,function(error){ if(!error){ console.log(“success!!”); } else console.log(“error”);} }); }); }); });
Callback hell can be avoided by following three ways:
Error-first is used to pass errors and data. if in any case when something went wrong programmers check the first argument and whereas additional arguments are used to pass data. An example is given below:
fs.readFile(filePath, function(err,data) { If(err) { });
Well, programmers must not try to listen on port 80 with Node JS, you need superuser rights to do so. This is always better to avoid this practice. But still if you want to listen this port then you can do it by running the application firstly on the port number above 1024 and then by putting Nginx like a reverse proxy.
Node.js runs through a single thread as per Node.js developer, but in real Node.js uses many threads through libuv. Every I/O require callbacks when you will put them into an event loop for execution. So, a chain of events is known as an event loop.
There must be low-level unit tests as well along with high-level unit tests as per test pyramid. For HTTP APIs it may be defined as:
Stubs programs or functions are used to stimulate module or component behavior. Canned answers of the functions are provided by stubs during any test case. You can also ensure why these stubs are called.
Here in this blog, we have listed the most popular questions that are frequently asked by interviewers. There could be many other questions for the Node.js interview that you need to practice to clear the interview in the first attempt only. You can take the example from the internet and even add many other questions as per your experience.
The questions that are covered in the above section are collected from the persons who have attended a Node.js interview. You can also get trained by some training institute like JanBask Training that would help you in understanding concepts in depth and clear the interview in one shot only. Today, this is one of the most in-demand platforms that can help you in shaping your career as a Node.js or IT professional.
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