10 Vue.js Interview Questions and Answers in 2023
1. Describe the differences between Vue.js and other JavaScript frameworks.
Vue.js is a progressive JavaScript framework that is designed to be incrementally adoptable. It is focused on the view layer of an application and is very easy to integrate into existing projects.
The main differences between Vue.js and other JavaScript frameworks are its size, speed, and flexibility. Vue.js is much smaller than other frameworks, making it easier to learn and faster to develop with. It also has a very flexible architecture, allowing developers to choose the best approach for their project.
Vue.js also has a very intuitive API, making it easier to use than other frameworks. It also has a great documentation and a large community of developers who are willing to help.
Finally, Vue.js is designed to be incrementally adoptable, meaning that developers can start using it in small parts of their project and gradually add more features as needed. This makes it easier to integrate into existing projects and allows developers to take advantage of the latest features without having to rewrite their entire application.
2. How would you go about debugging a Vue.js application?
When debugging a Vue.js application, I would first start by using the Vue.js devtools. This is a browser extension that allows you to inspect the component tree, observe data changes, and view the current state of the application. This is a great way to quickly identify any issues with the application.
Next, I would use the Vue.js error handler to identify any errors that may be occurring. This will provide detailed information about the error, including the line number and the stack trace. This can be very helpful in pinpointing the exact issue.
Finally, I would use the Vue.js console to log any data or events that are occurring in the application. This can be very helpful in understanding the flow of the application and identifying any potential issues.
Overall, these tools can be very helpful in debugging a Vue.js application and can help to quickly identify and resolve any issues.
3. What is the purpose of the Vue.js component lifecycle?
The Vue.js component lifecycle is a series of methods that are called at different stages of a component’s existence. These methods are used to perform tasks such as setting up data, creating and updating the DOM, and responding to user events.
The component lifecycle consists of eight different methods, each of which is called at a different stage of the component’s existence. These methods are:
1. beforeCreate: This method is called before the component is created and is used to set up initial data and state.
2. created: This method is called after the component is created and is used to set up data and state that is dependent on props or other external data sources.
3. beforeMount: This method is called before the component is mounted to the DOM and is used to set up the initial DOM structure.
4. mounted: This method is called after the component is mounted to the DOM and is used to set up event listeners and perform any other DOM-related tasks.
5. beforeUpdate: This method is called before the component is updated and is used to prepare the component for any changes that may occur.
6. updated: This method is called after the component is updated and is used to perform any necessary DOM updates.
7. beforeDestroy: This method is called before the component is destroyed and is used to clean up any event listeners or other resources that were set up during the component’s lifetime.
8. destroyed: This method is called after the component is destroyed and is used to perform any final cleanup tasks.
The component lifecycle is an important part of the Vue.js framework and is used to ensure that components are properly set up and cleaned up when they are no longer needed.
4. How would you implement a custom directive in Vue.js?
Creating a custom directive in Vue.js is a straightforward process.
First, you need to create a JavaScript file for the directive. This file should contain an object with the directive's name and a function that will be called when the directive is used. The function should accept two arguments: el, which is the element the directive is being applied to, and binding, which is an object containing the value and modifiers passed to the directive.
Next, you need to register the directive globally or locally. To register it globally, you can use the Vue.directive() method, passing in the directive's name and the object you created in the previous step. To register it locally, you can use the directives option in the component's options object.
Finally, you can use the directive in your template. To do this, you need to use the v- prefix followed by the directive's name. You can also pass a value and modifiers to the directive, which will be available in the binding argument of the directive's function.
For example, if you created a directive called my-directive, you could use it in your template like this:
And the directive's function would be called with the following arguments:
el: the div element binding: { value: value, modifiers: modifiers }
5. What is the difference between a single-file component and a regular Vue.js component?
A single-file component is a Vue.js component that is written in a single file, usually with a .vue extension. This file contains the HTML, CSS, and JavaScript code for the component, all in one place. This makes it easier to manage and maintain the component, as all the code is in one place.
A regular Vue.js component is written in separate files, usually with a .html, .css, and .js extension. This means that the HTML, CSS, and JavaScript code for the component are all in separate files, which can make it more difficult to manage and maintain the component.
6. How would you go about creating a reusable component in Vue.js?
Creating a reusable component in Vue.js is a straightforward process. The first step is to create a new Vue component. This can be done by creating a new .vue file in the components folder of your project. Inside the .vue file, you will need to define the template, script, and style sections.
In the template section, you will define the HTML markup for the component. This can include any HTML elements, as well as any custom components you have created.
In the script section, you will define the logic for the component. This includes any data, methods, computed properties, and lifecycle hooks that the component needs.
In the style section, you will define the CSS for the component. This can include any CSS rules that are specific to the component.
Once the component is defined, you can use it in other components by importing it and adding it to the components option. You can also register it globally so that it can be used in any component.
Finally, you can add props to the component to make it more reusable. Props allow you to pass data from a parent component to the child component. This allows you to customize the component for different use cases.
By following these steps, you can create a reusable component in Vue.js.
7. What is the purpose of the Vuex library and how would you use it?
The purpose of the Vuex library is to provide a centralized state management system for Vue.js applications. It serves as a centralized store for all the components in an application, with rules ensuring that the state can only be mutated in a predictable fashion.
Vuex is used to store and manage the state of an application. It provides a centralized store for all the components in an application, with rules ensuring that the state can only be mutated in a predictable fashion. It also provides methods for committing mutations to the state, and subscribing to changes in the state.
To use Vuex, you first need to create a store. This is done by creating a new instance of the Vuex.Store class and passing in an object containing the state, mutations, actions, and getters. Once the store is created, you can then use it in your components.
In your components, you can access the state of the store using the mapState helper. This helper allows you to map the state of the store to the component's computed properties. You can also commit mutations to the store using the mapMutations helper. This helper allows you to map the mutations to the component's methods.
Finally, you can subscribe to changes in the store using the mapActions helper. This helper allows you to map the actions to the component's methods. This allows you to react to changes in the store and update the component accordingly.
8. How would you go about creating a custom transition in Vue.js?
Creating a custom transition in Vue.js is a relatively straightforward process.
First, you need to create a transition component. This component should contain the transition code, and should be registered with Vue.js. To do this, you can use the Vue.js component API. The component should have two parts: the transition code, and the transition hooks. The transition code should contain the logic for the transition, such as the duration, easing, and any other parameters you want to set. The transition hooks should contain the code that will be executed when the transition starts and ends.
Next, you need to create a transition-group component. This component will be used to wrap the elements that you want to transition. The transition-group component should contain the transition component you created earlier, as well as any other components you want to transition.
Finally, you need to add the transition-group component to your Vue.js application. You can do this by adding the component to the components option in your Vue.js instance.
Once you have done this, you can use the transition-group component to wrap the elements you want to transition. When the transition starts, the transition code and hooks you created earlier will be executed.
Creating a custom transition in Vue.js is a relatively simple process, and can be used to create some interesting effects in your application.
9. What is the purpose of the Vue Router library and how would you use it?
The Vue Router library is a routing library for Vue.js applications that allows developers to create and manage routes within their applications. It provides a way to map URLs to components, allowing users to navigate between different views in the application.
Using the Vue Router library, developers can create routes that map to components, allowing users to navigate between different views in the application. Routes can be defined using the Vue Router's router-link component, which is used to create links between different views. The router-view component is used to render the component associated with the current route.
The Vue Router library also provides features such as route parameters, query strings, and navigation guards. Route parameters allow developers to pass data to components when navigating between views. Query strings allow developers to pass additional data to components when navigating between views. Navigation guards are used to control navigation between views, allowing developers to control which views a user can access.
In summary, the Vue Router library provides developers with a way to create and manage routes within their applications, allowing users to navigate between different views. It also provides features such as route parameters, query strings, and navigation guards, allowing developers to control which views a user can access.
10. How would you go about creating a custom filter in Vue.js?
Creating a custom filter in Vue.js is a relatively straightforward process.
First, you need to create a new file in your project directory and name it something like “filters.js”. This file will contain all of your custom filters.
Next, you need to import the Vue object from the Vue library. This will allow you to access the Vue.filter() method.
Once you have imported the Vue object, you can create your custom filter. To do this, you need to use the Vue.filter() method. This method takes two arguments: the name of the filter and a function that will be used to transform the data.
For example, if you wanted to create a filter that capitalizes the first letter of a string, you could do something like this:
Vue.filter('capitalize', function (value) {
if (!value) return ''
value = value.toString()
return value.charAt(0).toUpperCase() + value.slice(1)
})
Once you have created your filter, you can use it in your template by using the “v-filter” directive. For example, if you wanted to use the “capitalize” filter you created above, you could do something like this:
Hello World!
And that’s it! You have successfully created a custom filter in Vue.js.