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VOOZH | about |
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VOOZH | about |
Vue.js is a progressive, lightweight, and flexible JavaScript framework used for building modern web applications, making it an excellent choice for both single-page applications (SPAs) and complex web interfaces. Vue.js provides powerful features like the reactivity system, component-based architecture, Vue Router, Vuex (or Pinia) for state management, and server-side rendering (SSR) with Nuxt.js.
In this article, we’ve compiled the Top 50+ Vue.js Interview Questions and Answers - 2025, covering both fundamental and advanced Vue.js concepts. Whether you’re a beginner or have 2-5 years of experience, these questions will help you prepare effectively for Vue.js-related interviews.
Table of Content
Vue.js is a progressive JavaScript framework used to build user interfaces and single-page applications (SPAs). Vue.js is designed to be flexible, making it easy to integrate into projects, from simple views to complex web apps, and it focuses on the view layer, allowing developers to focus on building interactive and responsive applications efficiently.
Single Page Applications (SPAs) load once and robustly update content, reducing wait time for users. It uses JavaScript to fetch data and update the web page without necessitating to reload everything.
A component in Vue.js is a reusable piece of code that signifies a part of the user interface. Components make it simpler to handle complex applications by splitting them down into minor, controllable pieces.
To make a component in Vue.js, pursue these steps
Props in Vue.js are custom attributes that permit parent components to pass data to child components. They empower component reusability by producing it possible to handle child components from their parent. They are specified in the child component and received as arguments from the parent.
Syntax:
Vue.component('child-component', {
props: ['propName'],
// define component
});Feature | One-Way Data Binding | Two-Way Data Binding |
|---|---|---|
Definition | The data flows only from the component’s state (model) to the DOM (view). | The data flows both ways between the component’s state (model) and the DOM (view). |
Direction | Unidirectional (from model → view). | Bidirectional (from model ↔ view). |
Binding Method | Uses v-bind (: shorthand) to bind values to attributes. | Uses v-model to bind input elements to data properties. |
Use Case | Used for rendering static or read-only content (e.g., displaying values in <p>, <h1>, <img>, etc.). | Used for interactive elements like form inputs (<input>, <textarea>, <select>) where user input updates the data. |
Example | vue <p v-bind:title="message">{{ message }}</p> | vue <input v-model="userInput"> |
Routing in Vue.js is used to navigate the Vue application, permitting the formation of single-page applications with multiple views. Vue Router helps link between the browser’s URL/History and Vue’s components empowering for certain paths to render whatever view is linked with it. A Vue router is utilized in making single-page applications.
Vue.js instance is the root of all Vue application. It is JavaScript object formed by the 'Vue' constructor function and assists as the initiating point for building a Vue application.
Creating Vue Instance:
Vue.js filter is defined as Vue components that offer features called filters to apply text formatting on any part of the data templates dynamically. They are mainly applied in 'v-bind' expressions. Filters can perform tasks like formatting dates, capitalizing text.
{{ message | filterName }}After the data have been set and the DOM changed, the nextTick method is only easy solution to perform a function.
In Vue.js, the 'errorCaptured' lifecycle hook permits to control errors taking place in a component and its child components. For application-wide error handling, you can apply global error handlers like 'Vue.config.errorHandler' .
In Vue.js, custom events are formed applying the '$emit' method within a child component to activate an event. The parent component listens for this event using the 'v-on' directive or its shorthand '@' . This grants communication between a child and parent components.
In Vue.js, the Virtual DOM (VDOM) is an approach used to upgrade execution when updating web pages. It works like a blueprint of the real web page's structure, kept in memory. When a Vue component changes, Vue first update VDOM instead of directly editing the real DOM. Then, it matches the improved VDOM with the earlier one to figure out the smallest number of changes vital in the real DOM. This method lessens the number of upgrades to the existing web page, forming Vue applications rapid and more responsive, notably with often data changes.
Hooks are a new feature introduced in Vue.js 3. Hooks are functions that permit adding reusable logic to components. They permit managing state, lifecycle events, and side effects within functional components.
Some of the most typically used hooks include:
In Vue.js, a "key" is a unique attribute used mainly to discover nodes in a list of components rendered utilizing 'v-for' . When Vue renders multiple items with 'v-for' , it uses keys to capably update the DOM elements. Using keys correctly helps Vue efficiently update the DOM by reusing extant elements based on changes in data, rather than re-rendering everything from scratch, thus refining execution and stopping unneeded re-renders.
Feature | v-show | v-if |
|---|---|---|
Definition | Toggles the visibility of an element by modifying the display CSS property. | Completely adds or removes the element from the DOM based on the condition. |
DOM Manipulation | The element remains in the DOM but is hidden (display: none). | The element is created or destroyed dynamically in the DOM. |
Performance | More performance-efficient when frequently toggling visibility. | More performance-heavy when toggling frequently since it involves adding/removing elements from the DOM. |
Use Case | Use when visibility needs to be toggled frequently (e.g., dropdowns, tabs). | Use when elements are conditionally rendered based on logic (e.g., fetching API data). |
Example | vue <p v-show="isVisible">Hello World</p> | vue <p v-if="isVisible">Hello World</p> |
Feature | $emit | $on |
|---|---|---|
Definition | Used to trigger events from a child component to the parent. | Used to listen for events triggered by a child component. |
Direction | Child → Parent (emits events to parent component). | Parent → Child (listens to events from child component). |
Scope | Can only emit events in the current instance of the component. | Can listen for events emitted within the component instance or its descendants. |
Usage | Commonly used when creating child-to-parent communication. | Commonly used for parent listening to child component events (e.g., custom components). |
Example | vue this.$emit('customEvent', data); | vue this.$on('customEvent', (data) => { console.log(data); }); |
Evan You, the creator of Vue.js, developed the framework while working at Google on various Angular projects.
Local components are defined inside a specific component and are accessible only within that component or its child components.
A global component in Vue.js is a component that is registered globally, forming it accessible for use in any part of the application. This permits the component to be reused over varied templates without requiring to import it each time.
The 'data' function is applied to clarify the reactive data properties for a component. Such data properties are part of the component's state and can be acquired in the component. The 'data' function must return an object that covers the properties you seek to be reactive.
Vue CLI (Command Line Interface) is a tool for fast support Vue.js projects. This is a command-line utility that permits you to choose from a range of build tools. With Vue CLI, developers can rapidly set up a new project with best practices and modern build tools like Webpack or Vite.
To pass data between components in Vue.js, you can use several methods depending on the component relationship:
Slots are placeholders in a component's template that permit content to be passed into them from the parent component. They empower the formation of reusable components by giving a way to insert components into predefined slots. It can be named or unnamed ('default'), allowing versatility in how content is divided. This attribute is notably valuable for forming components that need dynamic layouts, where the structure might vary depending on where the component is used.
Asynchronous operations are usually controlled using promises or async/await syntax. Promises permit chaining of .then() and .catch() to handle asynchronous responses from APIs. Instead, async/await gives a cleaner syntax by permitting asynchronous functions to be written in a synchronous style.
A watcher is a mechanism designed to notice modifications in data properties in a component. It permits to respond to these modifications by enacting defined functions.
Syntax
export default {
data() {
return {
message: 'Hello GFG'
};
},
watch: {
message(newValue, oldValue) {
console.log(`Message changed from ${oldValue} to ${newValue}`);
// Perform actions based on the change
}
}
}
Vue Loader is a webpack loader for Vue.js that permits to write Vue components in '.vue' file format. It empowers Vue.js applications to use Single File Components (SFCs), which encapsulate HTML, CSS, and JavaScript into a single file. They compile these components into JavaScript modules that the browser can grasp, easing component-based development in Vue.js projects.
Vue directives, marked by the prefix v- . These directives form a perfect connection to the Vue instance, facilitating the formation of a responsive user interfaces that react to changes in data and user interactions.
Here are the major kinds of directives in Vue.js:
Server-side rendering in Vue.js includes rendering Vue components on the server before sending HTML to the client. This boosts first page load execution by delivering pre-rendered content.
Here are some of the features of Vue.js:
To robustly bind classes and styles in Vue.js, use the 'v-bind' directive. You can obtain class binding using any ':class' or 'v-bind:class' .
<div :class="{ active: isActive, 'text-danger': hasError }"></div>Use the :style or v-bind:style directive to use inline styles dynamically.
<div :style="{ color: activeColor, fontSize: fontSize + 'px' }"></div>To optimize Vue.js applications, fixate on lowering excessive re-renders using memoization.
Functional components in Vue.js are stateless, and have no lifecycle hooks, giving performance benefits for easy presentational tasks. Class-based components, on the other hand, are sustaining full Vue features like lifecycle hooks, state management, and more complex logic, adequate for dynamic, interactive components.
HOCs are functions that take a component and return a new component with boosted features. This pattern is energized by higher-order functions in JavaScript, which are functions that work on other functions.
Here are certain crucial strategies for component naming in Vue.js:
Render function returns virtual DOM node, regularly named VNode in the Vue ecosystem, which is an interface that permits Vue to write these objects in your browser DOM. They include all the information necessary to work with Vue.
Yes, you can call REST APIs. You can include it in your project by using the following command.
npm install axios --save
Implementing GET method using Axios in Vue JS
axios({ method: "GET", "URL": "https://httpbin.org/ip" }).then(result => {
this.ip = result.data.origin;
}, error => {
console.error(error);
});
In Vue.js, some of the array change detection and mutation methods are:
Vuex is a state management pattern and library for Vue.js applications. It acts as a central store for all the components in an application. It applies rules to verify that state changes occur in expected way. When merged with the Vue.js DevTools extension, it gives extra strong features.
Vue-navigation router's guards protect navigations by diverting or cancelling them. The three possible techniques to plug into router navigations are listed below.
In Vue.js, the 'errorCaptured' lifecycle hook permits to control errors taking place in a component and its child components. For application-wide error handling, you can apply global error handlers like 'Vue.config.errorHandler' .
To install Vue.js in your project, you can follow these steps:
<script src="https://cdn.jsdelivr.net/npm/vue@2.x.x/dist/vue.min.js"></script>
npm install vue
vue create my-vue-app
cd my-vue-app
npm run serveIt is normally not suggested to use 'v-if' and 'v-for' directives unitedly on the similar element in Vue.js due to potential operation outcomes. Here is why:
In Vue.js, event handlers are methods that are invoked in response to precise events initiated by user interactions. These events can comprise things like clicks, key presses, mouse movements, form submissions, and more. They are defined within the Vue instance and are normally stated in the methods object.
Output
Single File Components in Vue.js conclude a component's template, logic, and styles in a single ' .vue ' file. They boost modularity by arranging all features of a component in one place, refining readability. During build, tools like webpack process these files, allowing innovative features like hot-reloading. This way refines Vue.js development by supporting component-based architecture.
In Vue.js, the ' $parent ' property gives direct access for a child component to its direct parent component in a nested structure. This permits the child to interact with and use methods.
Developers can form and add global level features to Vue via Vue plugin. This can be utilized to add globally available methods to an application. VueFire, Vue plugin that adds Firebase specific methods and binding to the intact application, is an example of Vue plugin.
The 'v-cloak' directive in Vue.js hides components until they are compiled, preventing the display of compiled Vue templates on page load. It assures an effortless user experience by excluding the wavering outcome generated by delayed rendering, utilizing CSS to hide elements as far as Vue processing completes.
In Vue.js, event modifiers are directives that can be affixed to the v-on directive to change how events are controlled. Some usually used event modifiers contain:
Some popular testing frameworks for Vue.js comprises:
