Suspense for async components in Vue - Interactive Code Practice

Practice - 5 Tasks

1fill in blank

easy

Complete the code to wrap the async component with Suspense.

Vue

<template>
  <Suspense>
    <[1] />
    <template #fallback>
      <p>Loading...</p>
    </template>
  </Suspense>
</template>

Drag options to blanks, or click blank then click option'

ASuspense

Bdiv

Ctemplate

DAsyncComponent

Attempts:

3 left

💡 Hint

Common Mistakes

Putting a regular HTML tag instead of the async component inside Suspense.

Not using Suspense at all.

The async component must be placed inside the Suspense tag to enable fallback content while loading.

2fill in blank

medium

Complete the code to define an async component using Vue's defineAsyncComponent.

Vue

<script setup>
import { defineAsyncComponent } from 'vue'
const AsyncComponent = defineAsyncComponent(() => import('./MyComponent.vue'))

const componentName = '[1]'
</script>

Drag options to blanks, or click blank then click option'

AAsyncComponent

BMyComponent

CdefineAsyncComponent

Dimport

Attempts:

3 left

💡 Hint

Common Mistakes

Using the file name or import keyword as the component variable.

Confusing the function name with the component variable.

The variable holding the async component is AsyncComponent, which you use in the template.

3fill in blank

hard

Fix the error in the Suspense fallback slot syntax.

Vue

<template>
  <Suspense>
    <AsyncComponent />
    <template [1]>
      <p>Loading...</p>
    </template>
  </Suspense>
</template>

Drag options to blanks, or click blank then click option'

Av-if

B#fallback

Cslot=fallback

Dfallback

Attempts:

3 left

💡 Hint

Common Mistakes

Using v-if instead of the fallback slot.

Using slot=fallback attribute which is invalid in Vue 3.

The correct syntax for the fallback slot in Vue Suspense is <template #fallback>.

4fill in blank

hard

Fill both blanks to create a Suspense with a timeout and error component.

Vue

<template>
  <Suspense :timeout=[1]>
    <AsyncComponent />
    <template #fallback>
      <LoadingSpinner />
    </template>
    <template #[2]>
      <ErrorMessage />
    </template>
  </Suspense>
</template>

Drag options to blanks, or click blank then click option'

A3000

Berror

Cfallback

D5000

Attempts:

3 left

💡 Hint

Common Mistakes

Using 'fallback' as the error slot name.

Passing timeout as a string instead of a number.

The timeout prop expects a number in milliseconds (e.g., 3000). The error slot is named error to show error content.

5fill in blank

hard

Fill all three blanks to create a dictionary comprehension filtering async components by load time.

Vue

<script setup>
const components = {
  compA: defineAsyncComponent(() => import('./CompA.vue')),
  compB: defineAsyncComponent(() => import('./CompB.vue')),
  compC: defineAsyncComponent(() => import('./CompC.vue'))
}

const fastComponents = Object.entries(components).reduce((acc, [[1], comp]) => {
  if (comp.loadTime [2] 1000) acc[[3]] = comp
  return acc
}, {})
</script>

Drag options to blanks, or click blank then click option'

Aname

B<

Dkey

Attempts:

3 left

💡 Hint

Common Mistakes

Using 'name' instead of 'key' for the first destructured variable.

Using wrong comparison operator like > instead of <.

When using Object.entries, the first element is the key (here named 'key'). We check if comp.loadTime < 1000 and assign to acc[key].

Practice

1. What is the main purpose of the <Suspense> component in Vue?

easy

A. To show fallback content while async components are loading

B. To handle errors in synchronous components

C. To style components with CSS

D. To manage global state across components

Solution

1. Step 1: Understand what async components do

   Async components load their code or data asynchronously, which can take some time.

2. Step 2: Role of <Suspense>

   The <Suspense> component shows fallback content during this loading time to improve user experience.

3. Final Answer:

   To show fallback content while async components are loading -> Option A

4. Quick Check:

   Suspense = fallback content during loading [OK]

Hint: Suspense shows a placeholder while waiting for async parts [OK]

Common Mistakes:

• Confusing Suspense with error handling
• Thinking Suspense manages CSS or styling
• Assuming Suspense manages global state

2. Which of the following is the correct way to use <Suspense> with a fallback in Vue?

easy

A. <Suspense><AsyncComp /><template fallback>Loading...</template></Suspense>

B. <Suspense fallback="Loading..."><AsyncComp /></Suspense>

C. <Suspense><template #fallback>Loading...</template><AsyncComp /></Suspense>

D. <Suspense><AsyncComp fallback="Loading..." /></Suspense>

Solution

1. Step 1: Check Vue Suspense syntax

   Vue uses a named slot #fallback inside <Suspense> to show fallback content.

2. Step 2: Validate the options

   <Suspense><template #fallback>Loading...</template><AsyncComp /></Suspense> correctly uses <template #fallback> with fallback text and wraps the async component inside Suspense.

3. Final Answer:

   <Suspense><template #fallback>Loading...</template><AsyncComp /></Suspense> -> Option C

4. Quick Check:

   Fallback slot syntax = <Suspense><template #fallback>Loading...</template><AsyncComp /></Suspense> [OK]

Hint: Use inside Suspense for fallback content [OK]

Common Mistakes:

• Trying to pass fallback as a prop
• Placing fallback template after async component
• Using incorrect slot name like 'fallback' without #

3. Given this Vue template:

<Suspense>
  <template #fallback>Loading...</template>
  <AsyncUser />
</Suspense>

What will the user see while AsyncUser is loading?

medium

A. The AsyncUser component will show partial content

B. Nothing will be shown until AsyncUser loads

C. An error message will appear

D. The text 'Loading...' will be shown

Solution

1. Step 1: Understand Suspense fallback behavior

   While the async component is loading, the fallback slot content is displayed.

2. Step 2: Identify fallback content

   The fallback slot contains the text 'Loading...', so this text appears during loading.

3. Final Answer:

   The text 'Loading...' will be shown -> Option D

4. Quick Check:

   Fallback slot content shows during loading = The text 'Loading...' will be shown [OK]

Hint: Fallback slot content appears while async component loads [OK]

Common Mistakes:

• Expecting no content during loading
• Thinking partial async component renders
• Confusing fallback with error message

4. What is wrong with this Vue Suspense usage?

<Suspense>
  <AsyncComp />
  <template fallback>Loading...</template>
</Suspense>

medium

A. Fallback content must be a component, not a template

B. The fallback template must use #fallback slot syntax

C. Suspense cannot wrap async components

D. AsyncComp must be wrapped in a div

Solution

1. Step 1: Check fallback slot syntax

   The fallback slot requires the named slot syntax #fallback inside <template>.

2. Step 2: Identify the error in code

   The code uses <template fallback> instead of <template #fallback>, which is invalid.

3. Final Answer:

   The fallback template must use #fallback slot syntax -> Option B

4. Quick Check:

   Fallback slot needs #fallback syntax = The fallback template must use #fallback slot syntax [OK]

Hint: Use not for fallback slot [OK]

Common Mistakes:

• Omitting the # in fallback slot
• Wrapping async component unnecessarily
• Thinking fallback must be a separate component

5. You want to show a loading spinner while two async components load in parallel inside Suspense. Which approach correctly shows fallback until both finish loading?

hard

A. <Suspense><template #fallback><Spinner /></template><AsyncComp1 /><AsyncComp2 /></Suspense>

B. <Suspense><AsyncComp1 /><template fallback><Spinner /></template><AsyncComp2 /></Suspense>

C. <Suspense><AsyncComp1 /><AsyncComp2 /></Suspense><template #fallback><Spinner /></template>

D. <Suspense><template #fallback><Spinner /></template><AsyncComp1 /></Suspense><Suspense><template #fallback><Spinner /></template><AsyncComp2 /></Suspense>

Solution

1. Step 1: Understand Suspense behavior with multiple async components

   A single Suspense wrapping multiple async components waits for all to load before showing content.

2. Step 2: Check fallback placement

   The fallback slot must be declared once inside Suspense before the async components to show fallback while any are loading.

3. Final Answer:

   <Suspense><template #fallback><Spinner /></template><AsyncComp1 /><AsyncComp2 /></Suspense> -> Option A

4. Quick Check:

   Single Suspense with fallback wraps all async components = <Suspense><template #fallback><Spinner /></template><AsyncComp1 /><AsyncComp2 /></Suspense> [OK]

Hint: Wrap all async components in one Suspense with fallback slot [OK]

Common Mistakes:

• Placing fallback after async components
• Using multiple Suspense components separately
• Putting fallback outside Suspense