JavaScript interview questions

Hello pals! Lately, I’ve been thinking about what topic to choose for attracting your attention. To my mind this time I’ve picked pretty informative and striking article such as JavaScript interview questions. Guys, who intend to work with JavaScript, must be acknowledged with these interview questions for avoiding any confusion while aiming the job of their dream.

If you’re just starting working with JavaScript you will find answers for a junior level, or maybe you’re pretty well acknowledged with JavaScript then you’re on the intermediate level of using JavaScript, and if you professionally interact with JavaScript, welcome to get acquainted with the interesting info for advanced users. Whatever level you stick to, it will surely come in handy in finding out the answers to the most valuable questions.

 Anyways, if you just tend to achieve the job you have dreamed about, you must be aware of the main JavaScript interview questions. The interviews usually can be pretty stressful, so good preparation will make you feel confident during the interview. I will be really glad to help you with it.

 Let’s start our journey!

The questions I’m gonna introduce you below are the most highly requested during the interviews, so no confusion allowed during the important stage of your life, I will help you to gain the goal you have been aiming for. So I suggest you get familiar with these questions just right now, for not wasting the time.

1. What is JavaScript meaning?

JavaScript is simple in description, the object-focused programming language that allows you to embed interplay in static HTML pages. The general-purpose kernel of the language was built into Internet Explorer, Netscape, and other web browsers.

2. How JavaScript and Java differ?

3. What are the JavaScript peculiarities?

  • It’s an easy-to-interpret scripting language;
  • It is integral to and mingled with Java;
  • It is an accessible and open-spaced scripting language.

4. What does data types JavaScript support?

Here are depicted the major data types that are maintained by JavaScript:

  • Boolean – Demonstrates correct and invalid values;
  • Null – Forms its separate type consisting of a single null value;
  • Undefined – This value is like null, sets its own type. If a variable is declared, but nothing is written to it, then the value is undefined;
  • Symbol – The new rudimentary symbol data type is used to create unique identifiers;
  • String – It is the sequence of characters that make up the text. There are a variety of simple variables in JavaScript, and the String value is a wrapper for a string space;
  • Number – Portrays integral and floating-point values.

5. What are the ranges of a variable in JavaScript?

The range of a variable is the area of your program in which it is determined. JavaScript variable has only two ranges, these are global variables and local variables.

 6. How to design a cookie with the help of JavaScript?

A cookie is a small-sized simple data which sent from the web site and saved on a user’s computer by the browser which is used for entering the web site. The easiest way to build cookies using JavaScript is by committing a string value to the document. cookie object. General syntax:

 document.cookie = “key1 = value1; key2 = value2; expires = date”;

7. How to read cookies?

Since the value of the document.cookie is a cookie it appears to be easy to read. You can use this string any time to want to enter the cookie.

8. What kinds of typed language exist?

Simply, we can describe two types of typed language: static and dynamic. Let’s speak about them in short.

  • Defining of static appears in the that the final types of variables and roles are introduced at the compilation stage;
  • In dynamic typing, all types are detected during program accomplishment.

9. How host objects and native objects vary?

  • Native objects are those that are elements of the JavaScript language stipulated in the ECMAScript spec, such as String, Math, RegExp, Object, Function, etc.
  • Host objects are implemented by the lead time such as XMLHTTPReguest, window, and so on

10. Why you should not enlarge native JavaScript objects?

Elongating a native JavaScript object implies attaching properties/roles to its criterion. At a glance, this seems like a nice idea, however, in practice it is critical. Imagine that your code uses several libraries that extend Array.prototype by joining the same contains method. As a result, the code won’t work accurately if the function of these two methods is not the same.

11. What is the “load” event used for?

The load event occurs at the end of the document priming process. In this case, all gadgets in the document are in the DOM. And also you can load all images, links, and scripts.

12. What is the event loop?

An event loop is a single-threaded loop that controls the call stack and analyses if there’s any work to be done in the task line.

As you can see, the JavaScript interview questions don’t oblige you to give long answers. Talking about each point in short means you’re completely conscious of JavaScript work because you can compile a huge number of the info in short, accurate, and understandable answers.  


Talking about JavaScript, many people can imagine something difficult for understanding and perception, but those answers, mentioned above, show the opposite, this topic is acceptable even for non-professionals.

If you have decided to work in the web software field, precisely with JavaScript, and you’re patiently waiting on your first interview, all those JavaScript interview questions which I provided earlier will be a beneficial crib.

It’s out of the question that you may face some other common questions, but don’t be afraid to give a confident answer.

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Since you have some more time and wanna read some interesting information, I would like suggesting you this article: “Top-16 React JS interview questions.”

I hope my topic was worthwhile for your attention. Thanks for paying some minutes to my article.

Good luck and take care!

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