Hello, my dear friends! Today we will talk about a very interesting topic, about the interview. That article will be useful for JavaScript developers who worry about future interviews. I will write some tips and hope they can help you!

Must read: How to Convert String to JSON Object in Java

What is JavaScript?

According to Github JavaScript is the most popular programming language in the world as of late 2019. And for good reason:

• easy to use;
• has familiar syntax;
• can be used in a wide variety of programming environments.

But how did this all start? How do we go from JavaScript being a taboo programming language to the most popular programming language in the world? Let’s talk about his history and how it became so.

So first of all, what is JavaScript? JavaScript is the programming language of the web. It was created in 1995 and at the time it was predominantly used to add behavior to websites. Things like making it so that when we click a button something actually happens. This example is something we all take for granted now but it was a huge deal at the time when websites were super simple and predominantly read-only.

In order to understand why JavaScript is so important let’s take a look at how any standard website is built. We have the HTML which is the general structure of the page. We have something called CSS that controls the style of the page or how things look. And finally, we have JavaScript which can dynamically change both the structure and style of the page in response to user actions.

JavaScript is quite a bit more as well. All this rich dynamic behavior that you experience every day is driven by JavaScript.

In the past 10 years or so JavaScript applications started to get really complicated. So the community builds libraries that simplify how developers build these applications. Some examples of these libraries are familiar ones like React, View, Angular, and more. These libraries aren’t mandatory but they sure make your life a whole lot easier. In recent years JavaScript has become insanely popular thanks to engines like Node.js which allow developers to use JavaScript not only to build just websites but to use it for other things such as hosting standalone applications, talking to databases, and talking to other services.

The flexibility of JavaScript both on the front-end and the back-end have been a major contributor to its long-term success. So that’s what JavaScript is and how it came to be now let’s talk fundamentals.

In order to get started with JavaScript, you need to have a grasp on the language’s structure. The most basic building blocks of any programming language are called primitives. In JavaScript, the primitives consist of numbers like 1, 2, 3, 3.5, and 999. Strings as “hello world”. Booleans which are true and false values. List which is a series of things and objects which are supposed to be the containers for combinations of other primitives. Objects also let you create dictionaries of items so that you can quickly look them up later. Think of an object like a phone book. If you know a person’s name, you can look it up and find their associated phone number very quickly.

Outside of primitives, we have the usual control structures such as “if-else” statements which are used for branching logic for and “while loops” which are used to examine multiple objects in a list one at a time and “try-catch” statements which are used to handle unexpected errors during your program’s execution.

We use the terms “var”, “let”, and “const” to declare references to instances of primitives or objects. “Var” is outdated and rarely used. “Let” allows you to temporarily assign something that could be changed later. And “const” allows you to permanently assign something that will never change like the constant time.

The other important aspects of JavaScript are functions. Functions allow you to wrap a bunch of behavior into one variable. For instance, when you attempt to pay a bill on your bank’s website, the website may need to do several things such as verify your identify, make sure you have money in your account, and finally perform the transaction. These three sub-steps can be wrapped inside one function called pay bill. These three smaller steps can also be functions that do separate things. You can quickly see how we use functions to create some rich behavior.

JavaScript itself isn’t that complicated but it’s hard to know where to go next and there’s a ton of conflicting information out there.

What must a JavaScript developer know?

Follow the trends. It is extremely important to know what the world is like and to meet its requirements. The same applies to JavaScript. Developers must be constantly in development trends, interested in what is newly invented, and enriched with this knowledge. There are many options where to look for this information and sites, forums, and blogs for developers. Following the trends is another option to add new customers and delay the stray, because the product that was wildly popular will turn more than once.

Ability to work on different platforms and browsers. A skilled developer knows the intricacies of working on many platforms. Know where you need to fix something to make the product look complete on all browsers. So when a new platform for product promotion appears, the developer must study the features of working on it.

Communication skills. Yes, who would have thought, but no developer sits in silence for days on end. The ability to communicate with both the customer and the team is an extremely important trait of a professional.

HTML / CSS. This will not be about superficial knowledge, but about a clear algorithm. HTML and CSS are one of the components of working with JavaScript. The programmer must be able to vary them, change, add something if necessary, and without a high level of understanding of these programs, it will not work.

There are other programs that would be good to know, now they are only gaining popularity (but we have already talked about trends). We are talking about Bootstrap or other frameworks, LESS, SASS.

JQuery. JQuery is an extremely productive library, I have absorbed plugins, extensions, and shortcuts that speed up some features.

Node. js and Express are two frameworks that are the most popular when it comes to using JavaScript at the back-end. Ideally, to know the two of them, but it is better to know one perfectly than two anyway.

What questions the developer must prepare to listen to during the interview?

• How many and which programming paradigms play an important role in the work of a JavaScript developer?

Answer: Two, prototype inheritance (also: prototypes, OLOO) and functional programming (also: closing, functions of the first class, lambda).

• What can you say about functional programming?

Answer: Functional programming is extremely important for working in JavaScript. It helps with complex mathematical functions to create programs and helps to avoid data changes.

• What is the difference between classical inheritance and prototype inheritance?

Answer: In the first type of inheritance, instances pass from classes and create relationships of subclasses. And in the prototype inherited, instances pass from other objects.

• What are the benefits of functional programming do you know?

Attention! What I wanted to draw attention to is that in most cases, the interview questions will be about functional programming. So if you want to impress your employer, then study this question a little more.

Answer: functional programming greatly simplifies the development process, the quick finding of the problem and options for its solution, etc.

• When should you choose a prototype inheritance?

Answer: When functional programming does not find a solution to the query; when the object consists of more than one source; when inheritance is needed.

• The difference between two and one-way data binding?
  
  Answer: Two-way data binding is special in that when any changes are made to the code, they are automatically displayed on the product interface.
  With one-way data binding, only the model can make changes (it manages everything).

• How are asynchronous programming and JavaScript related?
  
  Answer: asynchronous programming means that the engine runs in an event loop. When a blocking operation is needed, the request is started, and the code keeps running without blocking for the result. User interfaces are asynchronous by nature and spend most of their time waiting for user input to interrupt the event loop and trigger event handlers. This plays an important role in JavaScript because it is ideal for working with the user interface.

Conclusion

So, I want to summarize everything written. The main factor that guarantees a successful interview is your qualification and knowledge of JavaScript with other programs. I hope the questions I have covered here will help you prepare for your interview. Do not worry, behave calmly and you will succeed.