Advanced JavaScript Interview Question To Hire Experienced Candidates

Advanced JavaScript Interview Question To Hire Experienced Candidates

RahulMay 15th, 20214 min read

JavaScript is the world’s most famous programming language. It is well known as the programming language of the web. But some non-browser environments also use it such as Adobe Acrobats, NodeJs, etc. The main fact that makes it so popular is that is simple to use. Even Facebook and Google use JavaScript to build compact and desktop-like web applications.

It is sure that JavaScript is simple but that does not mean that the hiring team must be full with the knowledge of JavaScript. It is not mandatory for the HRs or hiring team to have a grip on JavaScript. So what to do if the HR lacks the subject knowledge? How will they hire the best fit for the team?

Do not worry! You do not need to mug up the subject. You just have to go through some of the advanced JavaScript questions. Ask them to your applicant in the interview and just mug up the answers. You might get closer to your ideal teammate.  

What Should You Consider While Hiring JavaScript Developers?

Hiring your JavaScript developer just on the basis of his/her resume is not enough. Of course, skill is a must but more important is to check if your candidate is still updated and experienced. So, here are some of the things that you need to keep in mind while hiring a JavaScript Developer.

Understand For What You Are Hiring The Developer

JavaScript got popular due to its strength to build applications using only one set of technologies. But not all developers can build your web app from start to end. So, depending upon the application you want, you will have to hire your developer with any of this required expertise:

  • Front-end Developer: A front-end JavaScript developer is an expert in the design requirements of an application. The user-interface side of the application is developed by a front-end JavaScript developer.
  • Back-end Developer: A back-end JavaScript developer builds the database structure of the application. This developer is responsible for any functionality that runs on the server.
  • Full-stack Developer: A full-stack JavaScript developer is the one who will handle both the responsibilities of the back-end as well as the front-end developer. This developer will be responsible for the functionality that runs on the server as well as the design requirements of the application.

Look For Experienced Candidates

Besides looking for the skills, you would have to look for candidates that are experienced. Because experience is a skill that cannot be replaced by any other skills. By checking out on the experience box, you will help your company by hiring a candidate who is sure to work wonders as per his/her experience.

Check Out On The Developer’s Communication Skills

JavaScipt is a bit complex but it is necessary for the developer to possess good communication skills. This skill will help him/her to interact with the clients or the team with ease and express his/her ideas seamlessly. Issues and problems will also be communicated with ease.

Test The Technical Abilities

Make sure that your candidate is not just a bookworm. Just check if he/she is technically sound or not. For the same, you can take a coding test of your applicant on any good online code javascript sandbox. This will help you in deciding if your candidate is worth the position or not.

Advanced JavaScript Interview Questions You Must Ask To Hire Experienced Candidates

You must check the technical skills of your applicant by making him code on any of the best coding interview tool and also place your interview questions before him/her.

Here are some of the senior JavaScript developer interview questions you need to ask your candidates:

  1. What is a potential pitfall with using a type of bar === "object" to determine if the bar is an object? How can this pitfall be avoided?
  2. What is the ‘Strict’ mode in JavaScript and how can it be enabled?
  3. What will be the output of the code:
     var Y =1;
     If ( function F() {} )
     y += Typeof F; </span>
  4. Explain equality in JavaScript
  5. How to empty an array in JavaScript?
  6. What is the significance of, and reason for, wrapping the entire content of a JavaScript source file in a function block?
  7. Explain the difference between Object.freeze() vs const
  8. What will be the output of the following code?
     var X = { Foo : 1};
     var output = (function()
  9. Consider the two functions below. Will they both return the same thing? Why or why not?
    Function 1
     function foo1()
     return {
     bar: "hello"

    Function 2
     function foo2()
     bar: "hello"
  10. What are the differences between ES6 class and ES5 function constructors?
  11. In what order will the numbers 1-4 be logged to the console when the code below is executed? Why?

    (function() {
    setTimeout(function(){console.log(2)}, 1000);
    setTimeout(function(){console.log(3)}, 0);
  12. What will the code below output to the console and why?

    var arr1 = "john".split('');
    var arr2 = arr1.reverse();
    var arr3 = "jones".split('');
    console.log("array 1: length=" + arr1.length + " last=" + arr1.slice(-1));
    console.log("array 2: length=" + arr2.length + " last=" + arr2.slice(-1));
Wrapping Up

These are some of the questions you can ask when you are interviewing a senior JavaScript developer. But you have to make sure that you search for the correct answers before placing the questions. Live interview tools will also lend a platform to you for checking your applicant’s skills. Make the most of these facilities and choose the best out of all the developers.

To make it simpler use a two-step process to choose, sort, and select your ‘best’ out of all the ‘averages’. These two steps include:

  1. Test them using JavaScript assignments
  2. Ask them the Advanced JavaScript Questions

This is the best way to choose a developer who will fit in your team well. We hope your problem of deciding what to do and what to ask a senior JavaScript developer is solved after reading this blog.

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