Answers to the Best 21 Vue JS Interview Questions of 2023

Vue.js is a widely-used open-source JavaScript framework that developers leverage to create responsive user interfaces (UIs) and single-page applications (SPAs). It shares the popularity with similar frameworks like Angular and React. Vue.js offers numerous benefits like its small size, two-way data binding, virtual DOM, and component-based architecture. When making a choice between these three frameworks, it is crucial to evaluate specific project requirements and personal preferences since each has its own pros and cons. Therefore, it is up to the developer to decide the framework that best aligns with the project. Some common questions asked during Vue.js interviews include: What are Vue.js core concepts? What differentiates Vue.js from React or Angular? What benefits does Vue.js offer? What is Vue CLI? How is the component implementation important in Vue.js?

What exactly is Vue JS?

Vue.js is a dynamic open-source JavaScript framework that allows developers to create responsive user interfaces effortlessly. It is among the most commonly used frameworks in web development because it concentrates on the view layer of the application. Thanks to its seamless integration into larger front-end projects, it is an excellent choice for developers who need to create web applications or interfaces quickly. In case you need to hire remote developers to write code in Vue.js or other technologies, make sure to check out Works.

Installing Vue JS is an easy process. With Vue JS, developers can quickly build interactive web interfaces that are both easy to understand and construct.

Vue.js first came out in February 2014 and has since gained significant recognition among developers. Currently, it has over 197,000 stars and 32,000 forks on GitHub, making it one of the most widely-used and top-rated frameworks in the world.

What are the primary features of Vue JS?

These are some of the primary features of Vue JS:

• Virtual DOM

  One of Vue.js’s main features is its extensive use of virtual DOM (Document Object Model). Instead of controlling the original DOM directly, Vue.js copies the DOM into a JavaScript data structure. This duplicated DOM is subsequently utilized to implement adjustments to the original DOM, leading to quicker and more effective updates.
  
  Each time the program undergoes a modification, the JavaScript data structure is modified and compared to the original data structure. This feature provides users with an easy and straightforward means of editing the application.

• Data Binding

  Vue JS employs data binding through the utilization of the binding directive, v-bind. This technique allows the assignment of values to HTML attributes, customization of styles, and attachment of classes. Data binding provides a compact and efficient approach to link data with the view layer, allowing for a streamlined development process.

• Components

  Vue JS components are an essential element used to build custom elements which can be reused in HTML.

• Event Handling

  To listen to events in Vue JS, v-on is the added attribute for DOM elements.

• Animation/Transition

  When HTML elements are added, modified, or removed from the Document Object Model (DOM), Vue.js provides developers with a wide selection of methods to create transitions. To generate the intended transition effect, the Vue.js built-in transition component must be wrapped around the appropriate element. Moreover, developers can easily enhance the user interface’s interactivity by integrating third-party animation libraries.

• Directives

  Vue JS provides built-in directives such as v-if, v-else, v-show, v-on, v-bind, and v-model, which execute various functions in front-end development.

• Routing

  Via Vue-router, page navigation becomes effortless.

• Lightweight

  Vue JS script is light in weight and performs at a rapid pace.

• Vue-CLI

  By employing the Vue Command Line Interface (Vue-CLI), the Vue JavaScript framework can be effortlessly integrated and installed into your project. This command-line interface enables the swift and efficient construction and compilation of your project, equipping you with the essential tools required for the proper execution of Vue.

Vue JS Interview Questions and Answers at a Basic Level

1. What is the term used to describe a Vue app that is rendered on the server?

   A Vue.js application that has been server-rendered can be labelled either “universal” or “isomorphic”. These terms signify that the majority of the application code is operational on both the client and server sides.

2. Is TypeScript supported by Vue?

   Yes, Vue JS includes formal type declarations for TypeScript. This capability extends to Vuex, Vue-router, and Vue core.

3. What is the component system in Vue JS?

   The component system enables the simplification of complex programs into smaller, reusable, self-contained units.

4. What are props in Vue JS?

   Props pertain to a type of component whereby special attributes can be registered.

5. What is the process for enabling two-way binding on textarea, form input, and select elements?

   To accomplish two-way binding on textarea, form input, and select elements, developers can utilize the V-Model. This model can automatically determine the optimal method for updating components based on the type of input. With the V-Model, developers can seamlessly streamline their application development.

6. What event modifiers are accessible in Vue JS?

   The roster of event modifiers available includes:
   1. stop
   2. prevent
   3. capture
   4. self
   5. once
   6. passive

7. What is dynamic route matching in Vue JS?

   A dynamic route can be characterised by a dynamic segment designated by a colon (‘:’). This attribute enables a route to accept dynamic values, which can be useful for transmitting an ID along the route. Through this functionality, the route can match the dynamic segment and retrieve the dynamic value.

Vue JS Interview Questions and Answers at an Intermediate Level

1. What is the distinction between slots and scoped slots in Vue JS?

   In Vue JS, a slot in a child component refers to an unoccupied area that is populated with data provided by the parent component. While using conventional slots, the characteristics of child components can only be accessed via the standard slot built within the parent environment.
   
   Alternatively, a scoped slot allows developers to utilize data within the slot content and send data from the child component to the parent scope.

2. What is the difference between v-if and v-show in Vue JS?

   Vue JS provides developers with the v-if and v-show directives to determine whether components should be rendered. Although both directives serve the same purpose, they offer different functionality that is suitable for distinct use cases.
   
   V-if is useful for rendering components or hiding them upon condition. While using v-if decreases the initial rendering time, it is not the most effective option when elements need to be frequently hidden and displayed.
   
   On the other hand, v-show renders the element in the Document Object Model (DOM) and leverages Cascading Style Sheets (CSS) to determine whether the element should be visible based on the result of the expression. As all of the components are added to the DOM, v-show does not incur the initial rendering cost that v-if does. Moreover, the cost of showing and hiding components is lower as components do not need to be added or removed from the DOM.

3. What are functional components in Vue JS?

   Functional components provide an alternative structure to the traditional component setup, where they don’t require the production of a component instance or abide by the standard component lifecycle. These components are considered stateless, and they only render when they’re called upon.
   
   Instead of depending on an options object, developers can construct functional components utilising a basic function, which doubles as the component’s render function.

4. What are Single File Components (SFCs) in Vue JS?

   Similar to other components, Single File Components (SFCs) are self-contained and reside within their own files. The following are some of the advantages of utilising SFCs:

   1. Global Definitions:

      SFCs are registered globally, and they are allocated unique names.

   2. Robust Templates:

      In SFCs, developers can avoid relying on a single template property and can instead easily construct and manage template code.

   3. CSS Support:

      Developers can apply CSS styling to the component’s structure itself when using SFCs.

   4. Preprocessor Support:

      Developers can use preprocessors such as Babel, Sass, and others in SFCs.

5. Explain the Composition API in Vue JS.

   The Composition API is beneficial for better logic reuse, improved type inference and more flexible code organization.
   
   This set of APIs enables developers to construct Vue components using imported functions, rather than the conventional technique that involves specifying options. The Composition API includes the following features:
   

   1. Reactivity API (ref() and reactive()) –

      Developers can create reactive states, computed states, and watchers directly via this API.

   2. Dependency Injection (provide() and inject()) –

      Developers can use the reactivity APIs while leveraging Vue’s dependency injection system with provide() and inject().

   3. Lifecycle Hooks (onMounted() and onUnmounted()) –

      Developers can hook into the component lifecycle using these hooks.

6. Define Mixins in Vue JS.

   A mixin object can include any component options. A component utilising a mixin gets all of the mixin’s options combined with its own options.

7. How to Test if a Mutation Occurs in Vue JS?

   Mutations are functions that rely solely on their input arguments for delivery, making them straightforward to test. Additionally, they can be saved in a store for added convenience. Export these mutations as a named export as well as the default export to ensure that they can be accessed most efficiently.

Vue JS Interview Questions and Answers for Advanced Level

1. What is the reason for avoiding arrow functions when writing lifecycle hooks in Vue instances?

   Arrow functions are incapable of declaring their own ‘this’ because they are non-self-contained. As a result, they can only be used within the context of their parent function.
   
   When an arrow function (=>) is employed in a Vue app, problems arise because the term “this” does not bind to the Vue instance.
   
   For this reason, developers highly recommend using standard functions rather than arrow functions.

2. What are the methods to include animations in a Vue application?

   There are four ways Vue provides to add animations to an application:
   

   1. Transition and TransitionGroup –

      Components in Vue designed for managing enter/leave and list transitions.

   2. Class-based animations –

      Animations that activate CSS class addition.

   3. State-driven animations –

      Transition effects produced by interpolating values, such as a component’s style binding.

   4. Watchers –

      Watchers utilised to animate an element depending on its numeric state.

3. Define Plugins in Vue JS.

   Plugins provide a great opportunity for code reuse, just like the composition API. They enable more efficient development by simplifying application-level functionality addition. Evaluating a candidate’s understanding of these more advanced Vue features and how to utilise them to streamline codebase operations is possible with this Vue JS interview question.
   
   Plugins are commonly employed to provide functionality in an application. Object and function approaches can both be applied to define plugins, but they must both have an exposed install() function. This function is necessary to use the app.use() function and to incorporate additional properties.

4. Define Vue-loader.

   Using the webpack loader plugin Vue-loader, it is possible for developers to create single-file components in the Vue format.
   
   The Vue-loader library allows webpack to separate and process each of the three sections of a single component file – template, script, and style. This is done using various loader modules like SASS or SCSS loaders. Thanks to the configuration, developers can swiftly build applications using .vue files.
   
   Vue-loader not only enables static assets to be viewed as module dependencies, but also allows their processing with webpack loaders. Notably, within Vue-loader development, hot reloading is available, which is particularly advantageous for dynamic web applications.

5. Explain the most efficient approach to manage state in a Vue application.

   As an application’s features and codebase expand, state management becomes increasingly difficult. In such cases, using a network of dependent props and events may not be the most effective solution. Rather, maintaining centralised control over state becomes crucial.
   
   The recommended paradigm for centralising state management within the Vue ecosystem is Vuex, which is the official state management library.
   
   By using Vuex, a centralised state management system can be established, serving as a reactive component data store that updates automatically in response to any changes in state. In addition, multiple independent components can draw from the same core state store.

6. What methods can be utilised to optimize the performance of a Vue JS application?

   There are several reasons why a Vue application may respond sluggishly:
   
   1. Heavy reliance on third-party libraries that are either being misused or are excessively large.
   2. Presence of unoptimized and uncompressed images.
   3. Failure to implement lazy loading for image loading.
   4. Lack of code reuse across the program functionalities.
   5. The presence of multiple pages being loaded simultaneously.
      
      Effective resolution of these issues can significantly improve the Vue JS app’s performance.

7. What are some essential Vue JS directives?

   Here is a list of some of Vue JS’s critical directives:
   
   1. V-if directive manipulates the DOM elements by adding or removing them based on specified conditions.
   2. V-else directive displays content only when the expression adjacent to v-if resolves to false.
   3. V-show works similarly to v-if, but instead of adding or removing elements from the DOM, it uses the CSS display property to hide or show elements.
   4. V-for allows developers to iterate over items in an array or object.
   5. V-model is a powerful feature for establishing two-way data bindings.

Summing up

If you’re preparing for junior or senior-level Vue developer positions, referring to these interview questions and answers for Vue can prove to be useful.

One must acknowledge that open-ended Vue interview questions do not have a single right answer. Interviewers are more keen on understanding the rationale behind your responses. It’s best to be prepared to explain the approach you take when answering such questions.

While technical expertise is a critical aspect of the recruitment process, it is not the only factor considered by recruiters. Work experience and soft skills are also highly valued and given equal weightage when assessing a candidate’s suitability.

Are you a skilled and experienced Vue JS developer seeking a lucrative remote role? Look no further, as Works offers excellent opportunities. Our developers can earn above average wages in many countries while collaborating with some of the top companies in the United States. Don’t miss out on this incredible chance! Visit Works now to embark on a better career path.

FAQs

1. What is the use of Vue JS?

   VueJS is a popular front-end tool for its flexibility. It enables the creation of web interfaces, single-page applications, and even desktop and mobile apps when paired with an Electron framework. The HTML extensions and JavaScript foundation of VueJS make it an ideal choice for developers looking to create applications for diverse platforms.

2. Is Vue a library or framework?

   Vue JS is a framework built using JavaScript, used for developing single-page applications and user interfaces.

3. Which is the better option – Angular, React or Vue?

   Angular, React, and Vue are unique frameworks used to build front-end applications. Although they can be similar in some aspects, it is important to consider their differences before choosing one for your project. Hence, comparing and determining which is better for a specific purpose is unproductive.