Vue.js aka the Vue is a popular JS framework. It is used for developing dynamic UIs and single-page apps. Evan You created Vue.js had gained considerable popularity among developers because of its performance, simplicity, and flexibility.
Since Vue.js keeps on getting popular, it is becoming a trendy topic in the job interviews of front-end developer roles. Hence, if you are planning to give an interview for a Vue.js job, it is essential to have a better understanding of the framework’s features and concepts.
Here, we will help you to prepare for the Vue.js interview in your dream Vue.js Development Company. We’ve made a list of top and often asked Vue.js interview questions and answers. These questions will cover a whole range of Vue.js topics from basic to advanced concepts like Vue.js state management. By understanding these questions, you will be prepared to show your Vue.js skill set while giving your interview.
So, Let’s dive in and understand each Q and A step by step.
Frequently Asked Vue.js Interview Questions and Answers
Here’s the list of some top interview questions the Vue.js development company expects you to answer correctly if you want to be selected in the next round of the selection process.
1# What are lifecycle hooks in Vue.js?
Lifecycle hooks are the functions that each Vue instance executes through. Vue has 8 lifecycle hooks:
- Before create- Before create is the 1st lifecycle hook and it is called when an instance of Vue is created
- Created- It is called just after the ‘before create’ hook
- Before mount- It is invoked just before the instance is being mounted on DOM. The template was already completed before.
- Before updating- When the data changes need the DOM update before the updated method is called
- Mounted- This hook is the name given to a template once the data is filled in it.
- Updated- This method is called when the DOM is updated
- Before destroy- It is a location where you clean up the resources before terminating the Vue instance.
- Destroyed- This method is used when different Vue instances are destroyed.
2# What is Vue.js?
Vue.js framework for developing user interfaces that are created in JavaScript. It is a framework that is progressive. Vue.js is also responsible for your app’s view layer.
Vue.js can be used to develop single-page apps. Vue framework handles higher-level issues like easy DOM rendering, tools, reactive state management, server-side rendering, and client-side routing.
3# What are the advantages of Vue CLI?
Here are the advantages of using Vue CLI:
- It has a sizeable collection of plugins that helps with integration of top frontend tools
- @vue/cli scaffolding for easy and interactive projects
- Quick prototyping with zero configuration by using @@vue/CLI & @vue/CLI-service-global
- Developed on the top of expandable and web pack using plugins @vue/cli-service in a runtime dependency
- js projects may be managed and created using a whole graphical user interface
4# What is Virtual DOM?
DOM, the acronym of Document Object Model, is an interface that assists languages like JS to interact and update HTML documents.
Tree Nodes represent elements, and the interface lets us update them. Moreover, it comes with a lot of cost, and the page will minimize the speed by a notable number of essential DOM operations.
Vue framework overcomes the problem by keeping an effective representation of the document’s structure in the memory, where a vnode (virtual node) shows nodes in a proper document’s structure.
When any manipulation is needed, the operations and computations are executed in the memory of the Virtual DOM rather than a real DOM. It is faster, and allows the virtual DOM algorithm to search for several methods of modifying the real DOM structure.
Then this process is applied to the real and actual DOM tree. This improves the performance and that is why Vue and React are virtual DOM-based frameworks.
5# How to enhance the performance of a Vue.js app?
Your Vue app can get delayed due to different reasons:
- There are large number of compressed and unoptimized photos
- When you rely on multiple third-party libraries that are either too misused or large
- The feature of lazy loading is missing in your website
- You are not reusing the functions in the whole program, and it minimizes the redundant code.
- You are having different pages and they have to be loaded at once
6# What is the v-for directive used for in Vue.js?
V-for directive is an inbuilt directive in Vue.js, it is used to iterate over a specific object or an array.
7# Can you brief us with some popular Vue.js websites?
Here are some of the popular sites that use Vue.js framework:
Netflix, Trivago, Gitlab, Facebook, Adobe, Grammarly, and many more.
8# Name some of the popular alternatives of Vue.js
jQuery, React, Bootstrap, Angular, etc are some of the popular alternatives of Vue.js.
9# Explain some different types of directives in Vue.js
Here’s the list of various types of directives present in Vue.js. They are:
- Literal directives
- Empty directives
- General directives
- Custom directives
10# What are Vue.js hooks? Also can you list different in-built hooks?
Vue.js hooks are the modern functionality of this framework that was introduced in Vue.js 3.
It allows addition of state management and logic in the components in a reusable and more organized way. Hooks are quite similar to lifecycle hooks, however they help with reusable logic and encapsulation across various components.
This framework has multiple in-built hooks that can be used to add features in the components.
Here are some of the most popular hooks in Vue.js:
- onUpdated- This Vue.js hook is called as soon as the component is updated because of the changes in its state and props. We can use this hook for performing any required post-update works.
- Setup- It is one of the most important hooks that adds state management and logic in the component. The setup hook is called before any component is made, and it allows the definition of methods, reactive data, computed properties, and other logic.
- onUnmounted- It is called just prior to the component gets unmounted from its DOM. This hook is used to perform different necessary cleanup functions before the component eradicates itself from the DOM.
- onUpdated- onUpdated hook is called after the Vue component is updated because of the changes in its props and state. This hook helps in performing necessary post-update functions.
11# Explain the components in Vue
Majority of front-end frameworks have various component systems for handling the user interface layer.
Vue components are the basic building blocks of the UI of every app. Components will allow us to divide the User Interface into independent, smaller and reusable pieces. The part of components is not just Vue specific, but, Vue owns a component model that provides encapsulation of the logic in each component.
12# Why to use the ‘const’ keyword in this framework?
A ‘const’ keyword is then used to make constants.
13# Can we make a Vue.js custom filter?
Yes, it is possible to build custom filters in Vue.js
14# List the conditional directives in Vue.js
v-else, v-if, v-else-if, and many more are the most popular conditional directives in Vue.js.
15# How to create a modern Vue instance?
To make a new Vue instance, you have to utilize the function named Vue constructor. Here’s the instance:
const app = new Vue({ // Configurations and options go here });
16# How to handle events and user input in Vue.js?
For handling user events and input in Vue.js, you can directly leverage the v-on directive or @shorthand.
By integrating event listeners with methods, you can interact back to user interactions like input changes, keyboard events, and button clicks.
17# Explain vue-loader
It is a webpack loader plugin which allows us to make single-file components in a specific vue format. Style, script, and template are the 3 different sections of a particular component file. Webpack extracts and processes every section using different loader modules such as SASS or SCSS, so you can thank the vue-loader here.
Because of this configuration, we can make the authon apps using .vue files. With different static assets can be regarded as dependency modules with the vue-loader, and webpack modules can be used for processing them. Hot reloading also helps in easy development.
18# Explain an accurate way to manage state in an extensive vue app, and why to recommend using it?
Managing the state can become tough when an app’s size increases both in terms of codebase, features, and employing an eternal network of downstream and upstream props and events isn’t sensible.
It becomes essential to transfer the state management to a CMS when this situation arises.
Vuex in Vue framework is the official state management library for saving the states at one place in the Vue framework.
This library allows the preservation of one central state. It is then used by components for reactive data stores that update in the state changes. The central and same state store can be utilized by unrelated and multiple components.
19# What is vue plugin?
Developers can build and then add global functionalities to Vue using a Vue plugin. This is used to add universally accessible properties and methods of an app and options, mixins, assets, and many other custom APIs. VueFire, a plugin used in Vue to add Firebase specific methods and binds the whole app, is the best example of using a Vue plugin.
20# Why to use Mixins in Vue.js framework?
Mixins are the set of particular logic that is stored in a precise way. They are also re-usable to add various functions in your Vue components and instances. Mixins are essential as they provide a lot of functions. Here’s the list of primary functions of Mixins:
- They provide great flexibility
- Mixins facilitates us with easy adherence of DRY principle and makes sure that no one repeats the code
- It contains different options for Vue components
- Mixins provides a robust platform used for code reusability
- One can use Mixins in Vue.js safely as they do not affect the changes outside the defined scope
21# What makes the Vue framework superior to Angular?
As Vue.js has its huge in-built functionalities and support of the community, Angular is just an obvious alternative for creating enterprise-based apps. When the matter is of creating UIs and managing complicated problems, the Vue framework is a technically sound framework.
Final verdict
These are some of the frequently asked questions while the vue.js development service provider is taking Vue.js job interviews. So, go through these answers and smartly deliver them to the interviewer. Happy reading!