Slot fallback content in Svelte - Interactive Code Practice

Practice - 5 Tasks

1fill in blank

easy

Complete the code to show fallback content inside a slot when no content is passed.

Svelte

<slot>[1]</slot>

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

ANo content provided

Bslot

Cfallback

Ddefault

Attempts:

3 left

💡 Hint

Common Mistakes

Putting fallback content outside the <slot> tags

Using slot attributes instead of content inside the slot

The text inside the <slot> tags is the fallback content shown when no content is passed to the slot.

2fill in blank

medium

Complete the code to provide fallback content for a named slot called 'header'.

Svelte

<slot name="header">[1]</slot>

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

A<h1>Default Header</h1>

B<header>Header</header>

C<div>Header</div>

D<h2>Header</h2>

Attempts:

3 left

💡 Hint

Common Mistakes

Not matching the slot name attribute

Leaving the slot empty without fallback content

The fallback content for a named slot is placed inside the <slot name="header"> tags. Here, a header element is used as fallback.

3fill in blank

hard

Fix the error in the fallback content syntax inside the slot.

Svelte

<slot>[1]</slot>

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

AFallback content</p>

BFallback content<p>

C<p>Fallback content

D<p>Fallback content</p>

Attempts:

3 left

💡 Hint

Common Mistakes

Leaving tags unclosed

Placing closing tags without opening tags

The fallback content must be valid HTML. The <p> tag must be properly opened and closed inside the slot.

4fill in blank

hard

Fill both blanks to create a named slot 'footer' with fallback text 'Default footer'.

Svelte

<slot [1]="footer">[2]</slot>

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

Aname

Bfooter

CDefault footer

Dslot

Attempts:

3 left

💡 Hint

Common Mistakes

Using 'slot' instead of 'name' attribute

Putting fallback content as attribute value

The attribute 'name' defines the slot's name. The fallback text goes inside the slot tags.

5fill in blank

hard

Fill all three blanks to create a slot with fallback content that includes a paragraph and a strong tag.

Svelte

<slot>[1]<strong>[2]</strong>[3]</slot>

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

A<p>

BImportant

C</p>

D<div>

Attempts:

3 left

💡 Hint

Common Mistakes

Not closing the paragraph tag

Using incorrect tags like <div> instead of <p>

The fallback content uses a paragraph tag wrapping text and a strong tag for emphasis.

Practice

1. What does fallback content in a Svelte slot do?

easy

A. It disables the slot from receiving content.

B. It hides the slot completely when empty.

C. It duplicates the slot content automatically.

D. It shows default content if no slot content is provided.

Solution

1. Step 1: Understand slot usage in Svelte

   Slots allow external content to be inserted into a component.

2. Step 2: Role of fallback content

   If no content is passed to the slot, fallback content is displayed instead.

3. Final Answer:

   It shows default content if no slot content is provided. -> Option D

4. Quick Check:

   Fallback content = default display when slot empty [OK]

Hint: Fallback content appears only if slot is empty [OK]

Common Mistakes:

• Thinking fallback hides the slot
• Assuming fallback duplicates content
• Believing fallback disables the slot

2. Which of the following is the correct syntax to provide fallback content inside a Svelte slot?

easy

A. Fallback text here

B.

C. {Fallback text here}

D. Fallback text here

Solution

1. Step 1: Recall Svelte slot syntax

   Fallback content is placed between the opening and closing <slot> tags.

2. Step 2: Identify correct syntax

   Only <slot>Fallback text here</slot> correctly defines fallback content.

3. Final Answer:

   <slot>Fallback text here</slot> -> Option A

4. Quick Check:

   Fallback inside slot tags = Fallback text here [OK]

Hint: Fallback content goes between and tags [OK]

Common Mistakes:

• Using fallback attribute which doesn't exist
• Trying to use curly braces inside slot tags
• Placing fallback outside slot tags

3. Given this Svelte component code:

<!-- Child.svelte -->
<slot>No content provided</slot>

<!-- Parent.svelte -->
<Child>Hello World</Child>

What will be displayed when Parent.svelte is rendered?

medium

A. Hello World

B. No content provided

C. Nothing is displayed

D. An error occurs

Solution

1. Step 1: Check slot usage in Child.svelte

   Child component has a slot with fallback 'No content provided'.

2. Step 2: Analyze Parent.svelte usage

   Parent passes 'Hello World' as slot content to Child, so fallback is ignored.

3. Final Answer:

   Hello World -> Option A

4. Quick Check:

   Slot content overrides fallback = Hello World [OK]

Hint: Slot content replaces fallback if provided [OK]

Common Mistakes:

• Assuming fallback always shows
• Thinking slot content is ignored
• Expecting an error due to slot

4. Identify the error in this Svelte component using slot fallback:

<slot>Fallback content<slot>
<div>Extra content</div>

medium

A. Fallback content must be inside <div> tags

B. Missing closing tag slash on <slot> element

C. Cannot have extra content after slot fallback

D. Slot fallback must be empty

Solution

1. Step 1: Check slot tag syntax

   The <slot> tag is missing the closing slash on the closing tag (</slot>).

2. Step 2: Validate HTML correctness

   Proper closing tags are required; missing slash causes syntax error.

3. Final Answer:

   Missing closing tag slash on <slot> element -> Option B

4. Quick Check:

   Proper closing tags = Missing closing tag slash on <slot> element [OK]

Hint: Always close slot tags properly with [OK]

Common Mistakes:

• Ignoring missing slash on closing tag
• Thinking fallback must be wrapped in div
• Believing extra content after slot is invalid

5. You want a Svelte component to show a default message if no slot content is passed, but also include a button that only appears when slot content is provided. How can you achieve this?

hard

A.
Click me

B. Default message
{#if !$$slots.default}
Click me
{/if}

C. Default message
{#if $$slots.default}
Click me
{/if}

D. Default message
Click me

Solution

1. Step 1: Use fallback content inside <slot>

   Placing 'Default message' inside <slot> ensures it shows if no content is passed.

2. Step 2: Conditionally show button with $$slots.default

   Using {#if $$slots.default} checks if slot content exists, showing button only then.

3. Final Answer:

   <slot>Default message</slot> {#if $$slots.default} <button>Click me</button> {/if} -> Option C

4. Quick Check:

   Fallback + conditional slot check = Default message {#if $$slots.default} Click me {/if} [OK]

Hint: Use $$slots.default to detect slot content presence [OK]

Common Mistakes:

• Using wrong condition to show button
• Trying fallback as attribute
• Always showing button regardless of slot content