Vue Components Quiz

1. What is the primary purpose of a Vue component?

To reuse code and organize UI into modular pieces

To store the entire application state

To replace HTML entirely

To handle server-side rendering only

Vue components are designed to encapsulate functionality and structure, allowing developers to create reusable and modular pieces of the user interface. This promotes better organization of code, enhances maintainability, and facilitates collaboration, as components can be easily shared and integrated into different parts of an application.

Explanation

Vue components are designed to encapsulate functionality and structure, allowing developers to create reusable and modular pieces of the user interface. This promotes better organization of code, enhances maintainability, and facilitates collaboration, as components can be easily shared and integrated into different parts of an application.

2. Which lifecycle hook runs after the component is mounted to the DOM?

BeforeCreate

Mounted

BeforeMount

Created

The "mounted" lifecycle hook is called after a component has been added to the DOM. This is the ideal point to perform operations that require the component to be fully rendered, such as accessing DOM elements or making API calls that depend on the component's visibility.

Explanation

The "mounted" lifecycle hook is called after a component has been added to the DOM. This is the ideal point to perform operations that require the component to be fully rendered, such as accessing DOM elements or making API calls that depend on the component's visibility.

3. In Vue, props are used to pass data ______ from parent to child components.

In Vue.js, props serve as a mechanism for passing data from parent components to child components. This unidirectional data flow ensures that the child components receive the necessary information to render or function correctly, reinforcing the component hierarchy and maintaining a clear structure in the application.

Explanation

In Vue.js, props serve as a mechanism for passing data from parent components to child components. This unidirectional data flow ensures that the child components receive the necessary information to render or function correctly, reinforcing the component hierarchy and maintaining a clear structure in the application.

Submit

4. What keyword is used to emit custom events from a child component?

$emit

$on

$watch

$dispatch

In Vue.js, the `$emit` keyword is used by a child component to send custom events to its parent component. This allows the child to communicate changes or trigger actions in the parent, facilitating a clear and organized way to handle interactions within the component hierarchy.

Explanation

In Vue.js, the `$emit` keyword is used by a child component to send custom events to its parent component. This allows the child to communicate changes or trigger actions in the parent, facilitating a clear and organized way to handle interactions within the component hierarchy.

5. Which of the following correctly defines a component's local data?

Data: { count: 0 }

Data() { return { count: 0 } }

Props: { count: 0 }

Computed: { count: 0 }

In Vue.js, a component's local data is defined within a `data` function that returns an object. This allows each instance of the component to have its own reactive state. The other options, such as `data: { count: 0 }`, do not provide the necessary function structure for defining local data in a component.

Explanation

In Vue.js, a component's local data is defined within a `data` function that returns an object. This allows each instance of the component to have its own reactive state. The other options, such as `data: { count: 0 }`, do not provide the necessary function structure for defining local data in a component.

6. Props in Vue are ______ by default, meaning child components cannot modify them directly.

In Vue, props are designed to be passed from parent to child components as a way to communicate data. By default, they are read-only to ensure that child components cannot alter the data directly, promoting a unidirectional data flow and maintaining the integrity of the parent component's state.

Explanation

In Vue, props are designed to be passed from parent to child components as a way to communicate data. By default, they are read-only to ensure that child components cannot alter the data directly, promoting a unidirectional data flow and maintaining the integrity of the parent component's state.

Submit

7. What is a computed property used for in Vue?

To store raw data values

To perform calculations based on reactive data

To emit events to parent components

To define component props

Computed properties in Vue are used to derive values based on reactive data. They automatically update when the underlying data changes, allowing developers to perform calculations or transformations without manually managing state. This enhances efficiency and keeps the template clean by encapsulating logic within the computed property.

Explanation

Computed properties in Vue are used to derive values based on reactive data. They automatically update when the underlying data changes, allowing developers to perform calculations or transformations without manually managing state. This enhances efficiency and keeps the template clean by encapsulating logic within the computed property.

8. In Vue, the ______ method watches for changes in reactive data and runs a callback function.

In Vue, the `watch` method is used to observe changes in reactive data properties. When a specified property changes, the `watch` method triggers a callback function, allowing developers to execute code in response to data updates. This is particularly useful for performing asynchronous tasks or complex operations based on data changes.

Explanation

In Vue, the `watch` method is used to observe changes in reactive data properties. When a specified property changes, the `watch` method triggers a callback function, allowing developers to execute code in response to data updates. This is particularly useful for performing asynchronous tasks or complex operations based on data changes.

Submit

9. Which directive is used to bind a class conditionally in Vue?

V-if

V-bind:class

V-show

V-for

In Vue.js, the `v-bind:class` directive is used to dynamically bind classes to an element based on conditions. This allows developers to apply or remove classes based on the state of data properties, enabling responsive styling without manually manipulating the DOM.

Explanation

In Vue.js, the `v-bind:class` directive is used to dynamically bind classes to an element based on conditions. This allows developers to apply or remove classes based on the state of data properties, enabling responsive styling without manually manipulating the DOM.

10. What does v-model do in Vue?

Creates a one-way data binding

Creates two-way data binding between input and data

Defines component props

Renders conditional elements

v-model in Vue establishes a two-way data binding between form input elements and the component's data. This means that any changes in the input field automatically update the data property, and vice versa, ensuring that the user interface and data model remain in sync without requiring additional code for manual updates.

Explanation

v-model in Vue establishes a two-way data binding between form input elements and the component's data. This means that any changes in the input field automatically update the data property, and vice versa, ensuring that the user interface and data model remain in sync without requiring additional code for manual updates.

11. A ______ component is a stateless, reusable component that only accepts props and emits events.

A functional component in React is a simple JavaScript function that takes props as input and returns JSX. It does not manage its own state or lifecycle methods, making it stateless and reusable. These components are ideal for rendering UI elements and can emit events to communicate with parent components.

Explanation

A functional component in React is a simple JavaScript function that takes props as input and returns JSX. It does not manage its own state or lifecycle methods, making it stateless and reusable. These components are ideal for rendering UI elements and can emit events to communicate with parent components.

Submit

12. Which lifecycle hook is called before the component is destroyed?

BeforeDestroy

Destroyed

BeforeUnmount

Unmounted

The `beforeDestroy` lifecycle hook is invoked just before a Vue component is destroyed. This allows developers to perform any necessary cleanup, such as invalidating timers, unsubscribing from events, or releasing resources, ensuring that the component is properly dismantled and that no memory leaks occur.

Explanation

The `beforeDestroy` lifecycle hook is invoked just before a Vue component is destroyed. This allows developers to perform any necessary cleanup, such as invalidating timers, unsubscribing from events, or releasing resources, ensuring that the component is properly dismantled and that no memory leaks occur.