6 Vue.js Interview Questions (With Sample Answers)

Updated 25 September 2022

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Vue.js is an open-source JavaScript framework developers use to build interactive interfaces and single-page applications. Vue.js developers work with other software developers and project managers to write robust, secure and scalable code. If you are interviewing for a Vue.js developer or user-interface (UI) developer position, getting familiar with some frequently asked questions and learning how to answer them can help you prepare for your interview. In this article, we share various Vue.js interview questions, their sample answers and additional tips to help you prepare for your interviews.

6 Vue.js Interview Questions With Sample Answers

Vue.js interview questions include a combination of questions related to skills, technical expertise and experience that help the hiring managers decide if you are a suitable candidate for the job. They use these questions to determine your knowledge and professional background. You can use the following examples as a guide:

1. What are the key features of Vue.js?

Interviewers may ask you this question to see how well you understand the basic concepts behind Vue.js. In your answer, briefly explain the key features of Vue.js.

Example answer: 'One of the key features of Vue.js is its ability to create a virtual DOM, which helps render web pages quickly and improves application performance. It does this by taking a copy of the DOM and determining the elements to update instead of rendering the entire DOM every time the user interacts with the page. Every piece of the webpage or Vue application is a component that represents encapsulated elements. For example, in a social media app, the chat window, comment feed, buttons and friend list would be separate components interacting independently.

Using components, you can write scripts in HTML, CSS and JavaScript without creating separate files for each of them. It enables component reusability, which allows you to reuse chunks of code throughout the program. It also makes the code easier to read and understand. This framework has a solid tooling ecosystem that provides an extensive range of tools and new functionalities that users can implement. Vue.js also has comprehensive documentation and community support that users can use to become familiar with the framework.'

2. What are filters in Vue.js?

This question assesses how well you understand the simple functionalities provided by Vue.js. Define filters, highlight their importance and mention how to use them in Vue.js while answering this question.

Example answer: 'A filter is a JavaScript function created to modify the data output when displaying it on a browser. You can use filters to format or apply transformations to the data. It does not affect a component's data, but changes the output of the data displayed in the browser.

The two types of filters are local and global filters. You can define local filters within components and global filters before creating a Vue instance. An example of a use-case of filters includes transforming strings into various formats, such as lowercase, uppercase, capitalising, pluralising and truncating. One way to use filters in Vue.js is to include the filter method in the index.js file. The first argument is the type of modification and the second is the value that requires modification. Vue.js invokes this function when applied to the data.'

3. What are mixins? How do you use them in Vue.js?

This question assesses how well you are familiar with Vue.js features. When answering this question, define mixins, highlight their importance and mention how to use them in Vue.js.

Example answer: 'Mixins are chunks of well-defined logic that you can reuse throughout the program. These are similar to functions in C. For example, consider two components that perform the same task. You would write two functions for both components. Doing so results in code duplication. Instead, you can create mixins and reuse the same function across multiple components.

The two types of mixins are local and global mixins. You can import local mixins to use them within individual components. A global mixin is available to all components throughout a project. Start by creating an object for mixins and define functions within it. You can then use the mixins in the components.'

4. What are directives in Vue.js? Give some examples.

Interviewers may ask this question to determine how well you understand the concept of directives in Vue.js. While answering, define directives, highlight their importance and provide examples.

Example answer: 'Directives in Vue.js are special HTML attributes you can use to modify the behaviour of HTML elements in the DOM. When using a directive in Vue, use the prefix vue, followed by a directive name, to identify the type of directive. Some examples of built-in directives include v-show, v-model and v-for.

The v-show directive hides or shows HTML elements based on certain conditions. You can use the v-model directive to bind the value of the script to the Vue template. The v-for directive iterates over items such as lists, arrays, an array of objects and a range of numbers.'

5. How can you improve the performance of Vue.js applications?

Interviewers want to hire candidates who can optimise business processes and minimise costs. This question determines if you are proficient in code optimisation and improving the performance of applications. Provide details of how you would improve the performance of Vue.js applications in your answer.

Example answer: 'Developers can implement lazy loading, which delays the initialisation of resources or objects until a user requires them. This improves system performance and saves resources. Importing an excess of external libraries can cause the application to slow down. When implementing features in the web application, check if a feature is available natively in the browser before looking for external packages.

A web application that uses heavy images and videos can cause rendering issues. Compressing and scaling down images and videos is essential when using them. Code reusability is another good practice which helps reduce development time, costs and resources while improving user experience and quality. Using mixins makes the code reusable.'

6. How can you make your Vue application more secure?

Interviewers may ask this question to see if you know the security aspects of a Vue application. Begin by answering why security is essential for web applications and list some ways in which you can make your application more secure.

Example answer: 'Securing an application is necessary to prevent unauthorised attacks, data theft, hijacking of resources and data fraud. Cross-site scripting is an attack in which attackers insert malicious scripts into websites. You can prevent this attack by performing data sanitisation, which cleans unformatted, incorrect, corrupted or incomplete data from external users and transforms them into trusted values. You can do this by using the Vue sanitise library. You can also choose to include the content security policy in the HTML head, which works by declaring the dynamic resources allowed to load.

When using external libraries, make sure that they are up-to-date. This is to ensure that the security or improvements made reflect in the recent version. Another tip is to avoid using untrusted content as a component template.'

Tips To Prepare For A Vue.js Interview

Here are some tips that can help you prepare for a Vue.js interview:

Learn the STAR technique

The STAR technique, where STAR stands for situation, task, action and result, can help you be prepared to handle real-time situations related to the job. This approach allows you to prove your experience and skills for the job by providing real-life examples. For example, in response to behavioural questions, you can share relevant details, your responsibilities, the steps you took and the situation's outcome. Sharing this helps the hiring managers decide if you are suitable for the job.

Revise important concepts

Revising helps identify strong and weak areas and recall key points of the topics you have studied. For example, when preparing for a Vue interview, consider essential topics such as its architecture, key benefits, features, components, performance optimisation and security aspects. When revising, you may also refer to flow diagrams to help you understand the concepts better.

Understand the job role

When applying for a job interview, it is essential to understand the role and responsibilities of the position clearly. Consider adding keywords from the job description to your resume and cover letter, since interviewers often look for specific qualifications and skills.

Before an interview, it is also vital to understand the company's products and clients. You can do this by going through the company's website, connecting with its current employees and reading their white papers and blogs.

Please note that none of the companies, institutions or organisations mentioned in this article are associated with Indeed.