I’m a junior developer, what to expect in a React interview?

Jan 31, 2023

Interviewing for React positions as a junior developer can be a frightening experience, especially if you didn’t have many interviews in the past. That’s why we’ve put this guide on what to expect during your interview.

React Fundamentals

Understanding the fundamentals of React is essential for passing the interview. Some of the key topics you should be familiar with include components, state and props, lifecycle methods, and event handling.


State and props are two essential concepts. State is used to manage the internal state of a component, while props are used to pass data from a parent component to a child component.

Components are the fundamental building blocks of any React application. They are reusable blocks of code that can be used like lego blocks to build interfaces. It is essential that you understand how to create and use them. Also, remember to learn the difference between class and functional ones.

Lifecycle methods

Lifecycle methods are methods that are called at different stages of a component's life. Understanding when they are called and how to use them to your advantage is important for optimising the performance of any application.


Event handling is another essential concept. You should be familiar with handling events such as button clicks, form submissions, and mouse movements.

JavaScript and ES6

Don’t forget that JavaScript is the language that React is built on, so it's important to have a good understanding of it. Some of the key topics you should be familiar with include functions, objects, prototypes, and closures. Additionally, you should be familiar with ES6 features such as arrow functions, template literals, and the spread operator.


Functions are the backbone of JavaScript, and you should be comfortable writing and using them. Objects and prototypes are also essential concepts in JavaScript, and understanding how to use them will help you write better code.


Closures are a more advanced concept in JavaScript, but they are essential for writing efficient and concise code. Arrow functions, template literals, and the spread operator are all features of ES6 that can help you write cleaner and more maintainable code.


HTML and CSS are unavoidable fundamentals for building any web application, and React is no exception. While you don't need to be an expert in HTML and CSS, you should have a basic understanding of how they work. HTML is used to define the structure of a web page, while CSS is used to style it.


React applications often need to interact with APIs to fetch data and update the state of the application.

You should be familiar with how to make HTTP requests, fetch API, and other libraries such as Axios. Additionally, you should understand the basics of RESTful APIs and how to interact with them.


Testing is an essential part of any software development process, and React is no exception. You should be familiar with testing frameworks such as Jest or Enzyme, as well as testing methodologies such as unit testing and integration testing.

Unit testing is the process of testing individual components in isolation, while integration testing is the process of testing how components interact with each other. You should be familiar with both methodologies and know how to write and run tests using testing frameworks.


Git is a version control system that is widely used in the software development industry. Understanding the basics of Git is essential for any software developer, including React developers.

You should be familiar with Git basics such as branching, merging, and resolving merge conflicts. Additionally, you should understand how to use Git to collaborate with other developers and manage your codebase.


During a junior React interview, you may also be asked to complete a coding challenge or whiteboarding exercise. This can be a great opportunity to demonstrate your problem-solving and critical-thinking skills.

When completing a coding challenge or whiteboarding exercise, it's important to communicate your thought process and ask questions. This can show your ability to work collaboratively and learn quickly, which are essential qualities for any software developer.

In addition to the technical skills mentioned above, there are a few other key qualities that a junior React developer should possess. These include:

  1. Attention to detail: React applications often have complex user interfaces, so having a keen eye for detail is essential.

  2. Communication skills: As mentioned earlier, communication skills are important for explaining your thought process and collaborating with other developers.

  3. Eagerness to learn: React is a fast-moving technology, and new features and best practices are constantly emerging. Having a strong desire to learn and improve is essential for staying up-to-date.

In conclusion, preparing for a junior React interview can be daunting. Still, with a solid understanding of the key areas mentioned above, as well as the right mindset and soft skills, you can put yourself in a strong position to succeed.

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