vue js interview questions and Answers
Whether you are a multiyear experienced VUE JS developer or a fresher with the wish to reach new milestones of success in this niche, going through this expert advice content consisting vital VUE JS interview questions with answers, and other practice-oriented details can be extremely helpful. VUE JS is an open source and progressive JavaScript framework for building advanced user interfaces. It is designed to be incrementally adoptable. The core library of VUE JS is based on the view layer only and easy to integrate with existing projects and other libraries.
Most Frequently Asked vue js interview questions
VUE JS is a modern JavaScript Framework with the capability of building various web interfaces. Ranked among top web development tools, it uses virtual DOM for optimal performance and faster workability. It is also reactive and declarative rendering, which allows developers to create automatically updatable visual elements based on data or state changes.
Filters are functionality provided by VUE JS components that let users apply transformations and formatting to any part of template dynamic data. Filters don’t change component data or any other aspect, but they do affect the output.
Launched in 2018, VUE JS 2 has introduced a number of excellent features. Here are five best of them:
- Support for iterable object protocol with v-for
- Support multi-root templates
- No distinction between scoped vs. non-scoped slots
- Introduction of dynamic directive arguments
- Code frame in compiler warning messages
- Pre-fetching of data during server-side rendering
- ES module build intended for direct in-browser usage
In VUE JS, components independent, single units present in an interface. VUE components have their own markup, state, and style. These can be used to extend basic HTML elements to fully encapsulate the reusable code. VUE JS components are custom elements that compilers would attach to specified behaviors.
$emit in VUE JS is primarily purposed to send custom events between child components to parent components (upwards). This allows users to trigger a function in the parent component. Only API docs will only be required here.
To use raw HTML in a VUE JS template, users have to implement the v-HTML. We have to pass a reference to an HTML string in the data model to v-HTML present in component template.
Now, the raw HTML will be rendered into the component. Update the legacySystemHTML property and the HTML will update according to it.
Find high-quality VUE JS interview question and answers here for guaranteed career success.
<template>
<div v-html="legacySystemHTML"> </div>
</template>
<script> export default {
data() {
return {
// Just like JSX! Oh wait...
legacySystemHTML
<FONT color="#faddad" size="-2">
<MARQUEE>Please enter your name to continue.</MARQUEE>
... </FONT>
}
}
}
</script>
The absence of pedigree is probably the greatest benefit of using VUE JS rather than Angular JS. VUE JS is also extremely lightweight, user-friendly, and easy to learn. If your requirement is a single page and lightweight web application, then no doubt VUE JS is the best choice. Speed and performance will also be considered in favor of VUE JS when compare to Angular.
Here are the reasons to choose VUE JS over other front-end frameworks.
- Excellent learning curve
- Quality architecture and performance due to the presence of Virtual DOM
- Fastest growing development ecosystem and versatility
- Cross-platform mobile UI development
- Offers proprietary reactivity mechanism that automatically refreshes the user interface
- Impeccable UX production and high performance
- Increased productivity due to the use of HTML-based templates
- Blooming and active community
Developers can use router.push({ name: "yourroutename"}) or router.push("yourroutename") to redirect to another page or any particular route in VUE JS.
To create an instance of VUE JS, we have to use the below-mentioned function.
var vm = new Vue({
// options
})
In VUE JS, Props are the process in which developers pass data from a parent component to its child components (downward). The Props are added to the components in the section of the code.
Here, we are passing the prop “cool-prop” a value of “EXAMPLE”, which can be accessed from inside of my-component.
Virtual DOM is a data structure present in JavaScript. With this, the code will make changes to only the JS object, which makes it a budget suited option. Not only performance enhancement, but virtual DOM also offers additional functionality such as bypassing the need for a template property or an HTML template by using render() method.
It also offers users JavaScript’s programmatic power, flexibility to make code universal, JS extensions operation, and plenty more. Virtual DOM is an important chapter of VUE JS, which represents many VUE JS interview questions.
Developers use mixins in VUE JS to flexibly distribute reusable functionalities to distribute reusable functionalities. Mixins can contain any component options. Mixins can be maintained in one place so that all the components using it can be benefitted at the same time. Using it, we can also build a consistent API with component present throughout the app.
To deploy a VUE JS application, we have to use the following
syntax:-
npm run build
To use routing in VUE JS, we have to follow the below mentioned steps.
- Create three component files, as shown below.
// Home.vue
<template>
<h1>Home</h1>
</template>
<script>
export default {
}
</script>
- Now, create About.vue file with the following syntax.
// About.vue
<template>
<h1>About us</h1>
</template>
<script>
export default {
}
</script>
- Create the Contact.vue file with the below mentioned syntax.
// Contact.vue
<template>
<h1>Contact us</h1>
</template>
<script>
export default {
}
</script>
- To proceed, now update the update index.html file and continue by adding app id attribute.
- Import the Vue-router module in the main.js file from a node_modules folder and copy the below-mentioned code to the main.js file.
// main.js
import Vue from 'vue';
import VueRouter from 'vue-router';
Vue.use(VueRouter);
import Home from './components/Home.vue';
import About from './components/About.vue';
import Contact from './components/Contact.vue';
const router = new VueRouter({
mode: 'history',
base: __dirname,
routes: [
{ path: '/', component: Home },
{ path: '/about', component: About },
{ path: '/contact', component: Contact }
]
});
new Vue({
router,
template: `
<div>
<nav class="navbar navbar-toggleable-md navbar-light bg-faded">
<div class="collapse navbar-collapse" id="navbarNav">
<ul class="navbar-nav">
<li class="nav-item"><router-link to="/" class="nav-link">Home</router-link></li>
<li class="nav-item"><router-link to="/about" class="nav-link">About</router-link></li>
<li class="nav-item"><router-link to="/contact" class="nav-link">Contact</router-link></li>
</ul>
</div>
</nav>
<router-view class="view"></router-view>
</div>
}).$mount('#app');
- Run the code and get the final output.
In VUE JS, Lifecycle hooks are defined methods that get executed in a certain stage of VUE object lifespan. These act as a window into how the library that developers are using behind the scenes.
It’s a Webpack loader used to author VUE components in a Single-File Components (SFCs) format. Webpack and VUE-loader together ensure fast workflow for the development of VUE.JS applications.
| S.no | V-if | V-show |
|---|---|---|
| 1. | It is used for UI element rendering. | V-show is used to manage the display of a UI element. |
| 2. | V-if has else part | Doesn’t support “no else” part. |
| 3. | Only renders the elements that fulfill the condition. | It renders all elements and optimally manages with CSS “display” attribute. |
In VUE JS, Mounted refers to a VUE instance which is mounted to a DOM element, and that element is accessible as $el property on the VUE instance. It is called every time your component is loaded to the el.
There are certain cases in VUE JS, where JavaScript’s full programming power will be needed to build HTML. The render function is implemented here as an alternative of templates to successfully create dynamic components. Components with render functions will not have a template property or tag.
Compare to Angular and React, VUE JS is very small in size, thus highly improving its load time. In VUE, behavior and UI are both part of components, which makes properties intuitive. It is highly customizable also, allowing users to combine the component’s behavior and UI from within a script. VUE JS is easier to learn also, placing it top in simplicity and flexibility. The number of contributors is here also exceptionally growing in just a few years.
We can use the v-on directive to handle events in VUS JS. It helps in adding interactivity to web apps by responding to developer’s input.
Development History
Developed by former Google employee Evan You, VUE JS was initially released in February 2014. With continuous improvement and feature addition over the year, VUE JS is currently operating its version 2.6 released in Feb 2019 with the title of Macross.
Let’s further continue to discuss a set of most interviewer-preferred VUE JS interview questions with answers for your acknowledgment and practice. For your confirmation, these questions are handpicked by niche experts and accompanied here with their best-suggested answers.
Advantages:
- Extremely small in size (18–21KB), so easy to download and use it instantaneously. It’s small in size that doesn’t mean you have to compromise with speed. In fact, it beats most of the bulky frameworks such as Angular, Reacts and Ember.
- User-friendly, easy to understand, and develop apps.
- It facilitates developers to integrate with the existing applications built on JavaScript. This is possible because of the availability of components in VUE JS for everything.
- VUE JS offer comprehensive documentation, which is even easily understandable to users with very little knowledge of HTML and JavaScript.
- Because of MVVM architecture, VUE JS facilitates two-way communications, which makes HTML block handling easier.
- Users can write their own template in JavaScript and HTML file using virtual nodes.