Async components for lazy loading in Vue - Cheat Sheet & Quick Revision

Recall & Review

beginner

What is an async component in Vue?

An async component is a Vue component that loads only when needed, not at app start. This helps make the app faster by loading parts on demand.

beginner

How do you define an async component in Vue 3 using defineAsyncComponent?

You import <code>defineAsyncComponent</code> from 'vue' and wrap a dynamic import like this: <br><code>const MyComp = defineAsyncComponent(() =&gt; import('./MyComp.vue'));</code>.

beginner

Why use async components for lazy loading?

They reduce the initial load time by splitting code. Only the needed parts load when the user navigates to them, improving speed and user experience.

intermediate

What happens if an async component fails to load?

You can provide error and loading components to show messages or spinners. This keeps the UI friendly while waiting or if loading fails.

intermediate

How does Vue handle async components internally?

Vue treats async components as Promises. It waits for the Promise to resolve before rendering the component, allowing smooth lazy loading.

Which Vue function is used to create an async component?

A createAsyncComponent

B lazyLoadComponent

C asyncComponent

D defineAsyncComponent

Vue provides the function defineAsyncComponent to create async components for lazy loading.

What is the main benefit of using async components?

A Faster initial app load by loading components on demand

B Better styling options

C Automatic data fetching

D Improved SEO

Async components help by loading parts of the app only when needed, speeding up the initial load.

How do you handle loading states in async components?

A By refreshing the page

B By using CSS animations only

C By providing a loading component option

D By disabling the component

Vue allows you to specify a loading component to show while the async component is loading.

What syntax is used to import an async component?

A () => import('./MyComponent.vue')

B import('./MyComponent.vue')

C require('./MyComponent.vue')

D load('./MyComponent.vue')

Async components use a function returning a dynamic import, like () => import('./MyComponent.vue').

If an async component fails to load, what can you show?

A Nothing, the app crashes

B An error component

C The loading spinner forever

D The default HTML page

You can provide an error component to display a friendly message if loading fails.

Explain how to create and use an async component in Vue for lazy loading.

Think about how to load a component only when needed.

Describe the benefits and challenges of using async components in Vue.

Consider both performance and user experience.