Frontend Frameworks

About this test

ReactJS test: How it is structured and how it can help you hire your best candidate

Kandio’s ReactJS test lets you assess the candidates, employees, agencies, freelancers or students you have concerning any ReactJS task you might have.

Remember that Kandio offers guidelines on which programmers to proceed with, and which ones to discard. Kandio will give you reliable directions about things programmers should know about, but a programmer can be excellent, even if he does not know about all of these things.

We suggest that you use our tests before your interview process to know which ones actually to talk to. The final Kandio report should be a piece of conversation with the strong candidates, rather than a disqualifying process in a late-stage interview process.

ReactJS test details

React or ReactJS is a rapidly growing JavaScript library developed and maintained by Facebook. The use cases are growing as well as the support for the library as there are several strong advantages to utilizing React.

ReactJS is also the beating heart of React Native which is used throughout mobile development.

We hit up Yihua Zhang, which is one of the leading React consultants as well as one of the most successful instructors worldwide. Yihua created this test so you can get better and stronger candidates and at the same time, sign better employments with better people.

The ReactJS test consists of 20 challenging questions that Yihua believes are vital for a good React developer.

Who can benefit from this test?

  1. Any company looking to build a web application in React can use this test.
  2. Any hiring manager looking to assess a range of candidates within the vast React library.

The ReactJS test aims to help you evaluate if a candidate is aware of the pitfalls and complexities of using the basic building blocks of the React library. The test will also evaluate how well the candidate understands common architecture and coding patterns in React that are proven and tested to build scalable, maintainable and easy to work with React codebases.

Which areas are covered, and why?

Core Concepts
Knowing about React, a candidate must be familiar with how React works under the hood when it comes to updating the DOM. Candidates need to understand concepts like reconciliation, what the base React library can and cannot do, as well as how React as a library fits into the web development tool belt.

Component Behaviour
Components are the basic building blocks of React and they truly show how well a candidate understands React. Writing components represents almost 70% of what a developer will do in React, so a solid candidate needs to understand how these components work. An absolute must; how well candidates understand components determines how strong of a React developer they are.

Flux Architecture
Flux architecture is the most commonly used high-level architectural pattern used with React. Massively popular libraries like Redux that are core parts of the React ecosystem have been used extensively to build some of the largest React products in the world. They all rely on a solid understanding of flux and how it fits into working with React.

Nothing has shaken up the React community in recent years like the introduction of React hooks. React’s core team is pushing hard for teams to replace a lot of the existing ways of building React applications over to a hooks based solution, so understanding how they work and what they do is important with the changing climate of React.

Component Patterns
There are numerous patterns that can be used to build reusable components in React, but some are standard in the React ecosystem. There are numerous commonly used libraries in React that work off of these patterns. A solid understanding of what they are and their respective tradeoffs will show how well a candidate can write scalable and clean React code.

React can perform poorly if candidates do not understand how components are written, how React attempts to optimize for you, and what React specific pitfalls exist. Candidates should understand how to optimize the React code they write as well as when to optimize. We have included this in the ReactJS Test as it is essential to test how well a candidate understands how to build performant React applications.





Maximum completion time

39 minutes

Chapter(s) 6
  • Performance
  • Component Patterns
  • Component Behaviour
  • Hooks
  • Flux Architecture
  • Core Concepts
You might also like these tests:
Most recent React.js score
Component Patterns
Core Concepts
Component Behaviour
Flux Architecture
Try a sample question from our React.js specialist
In the Model-View-Controller(MVC) architecture for building applications, which section(s) does the React library represent?

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Made by one of the leading experts

As a self-taught developer, I’ve developed empathy towards aspiring talent and a keen eye on those with a lot of potential. Kandio provides me a platform to share my keen eye on developers with potential to other businesses.

Yihua Zhang

Yihua Zhang

Consultant of
Top rated ReactJS Instructor at Udemy
Author of our ReactJS test

Yihua Zhang

Yihua Zhang here. I’m a software developer and consultant for big-time tech companies worldwide. I’m an instructor on software development, though I’m always looking to teach something new every day.

As a self-taught developer, I know how challenging this field can be. Building, processing, troubleshooting, and fine-tuning the backbone of web applications require having the proper knowledge and expertise in the field of software development. All the concepts and skills I’ve learned from the field have been integrated into Kandio’s ReactJS assessment test, with the goal of helping you choose your next best developer.

My Experience

I chose a career in software development years ago, and I’ve been in this field ever since. My projects, with several global tech companies, involve working on Angular, React and React Native, JavaScript, and Redux, among others. I’m also an instructor for the developers’ community over at Udemy, and my passion is to empower others in having a fulfilling career in this field.

  • June 2018 - Present
    Top rated ReactJS instructor
  • February 2017 - Present
    Software Developer and Consultant
  • October 2015 - January 2017
    SkyPrep Training Software
    Software Developer

My Achievements

Choosing a career in software development turned out to be one of the best decisions I’ve made. Apart from working with large-scale global tech companies, I also take pride in inspiring other people into pursuing software opportunities.

  • June 2019
    Reached 10k students on my courses
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94% of all questions our support receives, can be answered in the below FAQ

I have many candidates - will they all receive the same questions for equal assessment?
Short answer:

Yes, all candidates are equally assessed, when you use Kandio.

Long answer:

All our tests have different questions that might or might not change from vacancy to vacancy.

However, once you lock a recruitment round in, the questions will lock in as well for all candidates going through your assessment, so that they are equally screened.
How can the exam score help me to make a better hiring decision?
Overall it would be best if you kept in mind that Kandio offers help with assessing your total pool of candidates. The point with this plan-of-attack is to give you a tool that will enable you to pinpoint the very underqualified candidates quickly, and promptly discard of them. As well as locating the strong candidates, and invite them for an interview before your competitor does.

The difficulty of our tests is serious in general and is meant to find the lesser qualified. So you shouldn’t disqualify a candidate at 67%, just because you have someone who’s testing 70%. Or even 85%.

Kandio is a tool you should use in addition to other means such as:

- Common sense
- Gut feeling
- Internal screening
- Other assessment tools from Mandomedio
- Experience of the candidate
- Career goals of the candidate

The reason we have priced Kandio the way we have is that it’s meant to be used alongside other decision factors, and not as a sole dictation of which candidate to employ.
Why Kandio over other tests? And why not a free-writing test?
All Kandio assessments have a difficult multiple-choice approach and a very clear and tangible scorecard at the end. We only work with objective measurements and completely disregard candidate values such as consistency in work, ability to teamwork, humanity, and care for colleagues, sociality, and the likes.

The reason for this is that in today's tech-oriented world, we often see a significant amount of different solutions to the same problem. If we offered free-write assignments, candidates would need to be assessed one by one, which obviously would be impossible at our price point.

With us, you're buying access to a robust set of exams, written by the world's best authorities, with well-functioning scorecards to make recruitment easier. And on top of that, we are using big-data to benchmark all your candidates across other similar candidates.
How difficult are the tests Kandio offers my candidates?
All our tests are authored with serious difficulty in mind. We accept only the best test authors onto our platform, and a fixed percentage of revenue goes directly to our authors to keep content updated, and authors happy.

Our goal is to weed out the least competent candidates in the most common knowledge within your desired field.

Because of this, you should keep in mind to adjust your salary expectations and level of acceptance, if you’re looking for junior roles, mid-level roles, or senior roles.
How do I adjust the level of my test to match the qualifications of the position I’m trying to fill within my company?
You don’t. Our tests are made with such difficulty in mind, that they would challenge all skill levels regardless of seniority. We almost never see any candidate getting everything correct on our exams.

If you are trying to fill a senior role, you would probably want candidates to score above 60% in Kandio. If you’re looking for a junior role, you could probably settle with 30%-50%

If you want a very junior role, that you can train along the way, you would be looking at 30%-50%.

We wouldn’t recommend considering any candidate below 20% unless you have clear indications from other factors of decision making.