Prepare for Vue.js Interview : most asked interview Question and answer for Freshers

Prepare for Vue.js Interview : A progressive JavaScript framework for creating user interfaces is called Vue.js. It can be used to start small with a single-file component and grow up to complex applications as needed because it is designed to be progressively adoptable. Its component-based architecture, which encourages modularity and reusability, is one of its main advantages. Components simplify codebase management and maintenance by being self-contained blocks of code that encapsulate their own HTML, CSS, and JavaScript. Declarative rendering is also used by Vue.js, where templates that resemble HTML are used to define the intended state of your user interface. This lessens the amount of manual DOM manipulation and streamlines development.

A software expert with expertise in creating user interfaces with the Vue.js framework is known as a Vue.js developer. They are quite knowledgeable on HTML, CSS, JavaScript, and the fundamental ideas behind Vue.js. Designers, developers, and maintainers of interactive online apps and components are the responsibility of Vue.js developers. They employ the declarative rendering, reactivity, and component-based design of Vue.js to build UIs that are effective, scalable, and easy to use.

here are some Question to Prepare for Vue.js Interview : most asked interview Question and answer for Freshers

1.Why is Vue.js called a progressive framework?

Because it enables developers to embrace Vue.js progressively and incrementally—beginning with a tiny piece of functionality and subsequently growing its usage as needed—the framework is known as progressive. This strategy has a number of benefits:

First of all, it lets developers study and comprehend Vue.js at their own speed. As their project expands, they can start with basic elements and progressively investigate more sophisticated aspects. Vue.js is accessible to developers of all expertise levels, from novices to seasoned pros, thanks to its progressive learning curve. Second, the danger of making major modifications to an already-existing project is reduced with the gradual adoption of Vue.js. Without changing the functionality of the entire application, developers can include Vue.js components into their current codebase. This methodical methodology lowers the possibility of mistakes and facilitates the management of the switch to a Vue.js-based design.

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2.What is the difference between one-way data flow/ or one-way data binding and two-way data binding?

The user interface (UI) portion of the program does not automatically refresh when there is one-way data binding or one-way data flow. In this paradigm, you have to create new code each time the data model is modified in order to update it. When utilizing Vue.js for one-way data flow or binding, the v-bind directive is employed.

In contrast, when the data Model is modified in two-way data binding, the application’s display (UI) component is automatically updated. Vue.js uses the v-model directive for two-way data binding.

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3.What is Vuex?

A state management library called Vuex was created especially for Vue.js applications. It makes it simpler to control data flow and maintain component synchronization by offering a centralized store for maintaining application-wide state. Because Vuex centralizes state, components can access and change it without really changing it. This encourages a codebase that is more predictable and manageable. In order to guarantee that state modifications are carried out in an organized and predictable way, Vuex additionally introduces ideas like mutations and actions. Actions are asynchronous functions that have the ability to commit mutations to update the state, whereas mutations are synchronous functions that alter the state directly. This division of duties contributes to the upkeep of an orderly and transparent governmental administration structure.

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4. What are filters in Vue.js?

Functions called filters in Vue.js can be applied to expressions inside templates to format or alter data before it is seen. They’re a practical approach to manage routine data operations right within your templates, which will improve the readability and conciseness of your code.

With the help of Vue.js components, you can apply formatting and changes to your dynamic template data using the Filters capability. There are two applications for filters: v-bind expressions and mustache interpolations. Filters only have an impact on the output; they don’t modify any component data or anything else.

5.What is Vue-loader in Vue.js?

A potent pre-processor for Vue.js components is called vue-loader. Its support for features like single-file components, template compilation, CSS extraction, and custom loaders gives you greater freedom and organization when writing Vue components.

One popular method of grouping Vue components is using single-file components (SFCs). They are divided into three primary sections: the style, the script, and the template. These sections are processed by Vue-loader, which then condenses them into a single JavaScript module. Your Vue components will be easier to manage and maintain as a result.

6.What is an SFC?

The acronym for Single-File Component is SFC. This method of combining Vue.js components into a single file is well-liked and effective. Usually, this file is divided into three primary sections:

• Template: The component’s HTML structure is described in this section. This is the area designated for writing markup that will be shown on the page.
• Script: The component’s JavaScript logic is contained in this section. The reactive elements that govern the behavior of the component are defined here, along with data, methods, and computed properties.
• Style: You can use CSS to style the component in this area. To make sure that styles only apply to the components’ elements, you may either use scoped styles or define styles specifically for the component.

7.What are computed properties?

In Vue.js, computed properties are a unique kind of property that are computed dynamically based on other properties in the data of your component. They offer a declarative method for defining dependent derived values.
Vue.js computes a calculated property’s value automatically when it is accessed, taking into account the component’s current state. Vue.js will recalculate the value and update the view if any of the computed property’s dependencies change. By doing this, the UI is guaranteed to always display the component in its most recent state.

8.What are watchers?

A useful feature in Vue.js for tracking changes to data attributes inside a component are watchers. They let you to perform particular actions each time a watched property’s value varies.

A watcher is defined as an object in the options of the component, where the values are callback methods that are called when the property changes, and the property names correspond to the properties you wish to watch.

9.What is the use of the v-for directive in Vue.js?

The Vue v-for directive.Lists and data iterations are rendered using JavaScript. It enables you to produce dynamic content by using an iterable, array, or object as a basis. You can quickly construct several pieces or components based on the structure of the data by tying a template to a data source.

The data source is items, and item is an alias for the item that is currently being iterated over. The v-for directive accepts a syntax of the form item in items. In order to retrieve the item’s position or a unique identification, you can also optionally specify an index or key. This gives you the ability to easily manage list updates and customize the generated result.

10.Can we create a custom filter in Vue.js?

Yes, Vue.js allows you to construct custom filters. Filters are reusable functions that you can apply to data in your templates to format or change it. This is particularly helpful for formatting text strings, dates, or numbers.

A custom filter is defined as a JavaScript function that is registered globally (through the Vue.filter() method) so that it is accessible across your entire Vue.js application; alternatively, if you only need the filter locally in a particular component, you can register it there. Once registered, you can apply the filter in your templates by applying it to data that has the pipe character (|).

11. What is the use of the ‘const’ keyword in Vue.js?

When you use the const keyword for a variable in Vue.js, you are effectively creating a constant reference to the value, meaning it cannot be changed later in your code. This helps to improve code readability, maintainability, and prevent accidental modifications.The main use of the const keyword in Vue.js is to declare variables whose values should not be reassigned.

While the reactivity system in Vue.js can occasionally support reassigned values, it’s generally accepted that using const whenever feasible will help you avoid potential problems and write more predictable code. Reassignment of variables can result in unexpected behavior, especially if they are used as keys for computed properties or watchers.

12.What is Virtual DOM?

A common programming method in contemporary UI frameworks, such as Vue.js, is Virtual DOM (VDOM). It functions as an in-memory replica of the real Document Object Model (DOM), which is a structure like a tree and represents the HTML components on a page.

When compared to manipulating the real DOM directly, the VDOM is quicker and more effective. The framework updates the VDOM, determines the minimal set of differences between the old and new VDOMs, and applies those changes to the real DOM whenever a component’s data or state changes. This procedure, called “diffing,” reduces pointless DOM processes, making user interfaces more responsive and efficient.

13. What is a Single-Page Application?

A single HTML page loads in a single-page application (SPA), which dynamically refreshes the page’s content as the user interacts with it without necessitating full page reloads. This produces a user experience that is more responsive and seamless than that of a desktop program.

In contrast to conventional websites, which load a fresh HTML page for every navigation, SPAs retrieve data from the server on demand and dynamically update the DOM (Document Object Model) using JavaScript. As a result, the user interface loads more quickly, pages transition more quickly, and it looks better.

14.What is a Vue instance? 

The core component of a Vue.js application is a Vue instance. ViewModels are JavaScript objects that link your data and the view, or user interface, that they represent. An options object that specifies the functionality of the component—including its data, methods, computed attributes, lifecycle hooks, and more—is passed in when you create a Vue instance.

Consider a Vue instance as a container for the data and logic of your component. It is in charge of rendering the template, controlling user interactions, and maintaining the reactive data. You may construct sophisticated, modular apps with reusable components by setting up numerous Vue instances.

15.What is a template in Vue.js

In Vue.js, a template is a declarative means of defining the layout and contents of a component’s UI. It is built in a syntax similar to HTML and binds data to the DOM using unique directives unique to Vue.

After templates are compiled into virtual DOM representations, the browser can be rendered with efficiency. This enables dynamic updates in response to modifications made to the component’s data. Templates offer a versatile means of creating intricate user interfaces; they can contain standard HTML elements, directives unique to Vue, and even bespoke components.

16.What are Routers?

The Vue.js router is a library that makes it possible to implement client-side routing in Vue.js applications. In this context, routing refers to the process of mapping URLs to particular components or views within the application. Routing makes it possible for users to switch between different pages or views without having to reload the entire page, which makes it feel more like a desktop or mobile application when the page doesn’t refresh. It also improves performance.

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