Named slots in Svelte - Cheat Sheet & Quick Revision

Recall & Review

beginner

What is a named slot in Svelte?

A named slot is a way to define multiple placeholders inside a component where different content can be inserted by the parent component. Each slot has a unique name to identify it.

beginner

How do you define a named slot inside a Svelte component?

Use the element with a name attribute, like . This creates a placeholder named 'header' for content insertion.

beginner

How does a parent component provide content for a named slot?

The parent wraps content inside an element with the slot attribute matching the slot's name, for example:

Content

.

intermediate

What happens if a named slot is not filled by the parent component?

The content inside the named slot element in the child component acts as a fallback and is displayed instead.

beginner

Can you have multiple named slots in one Svelte component?

Yes, you can define multiple named slots with different names to allow the parent to insert content in several places inside the child component.

How do you specify a named slot inside a Svelte component?

A <slot name="example"></slot>

B <named-slot>example</named-slot>

C <slot id="example"></slot>

D <slot-example></slot-example>

Named slots use the element with a name attribute to identify the slot.

How does a parent component provide content for a named slot called 'footer'?

A <slot name="footer">Content</slot>

B <footer slot="content">Content</footer>

C <div slot="footer">Content</div>

D <div name="footer">Content</div>

The parent uses the slot attribute with the slot's name on the element wrapping the content.

What is shown if the parent does not provide content for a named slot?

A The fallback content inside the slot element in the child component

B An empty space with no content

C An error message

D The first slot's content

Fallback content inside the named slot is displayed if the parent does not fill it.

Can a Svelte component have multiple named slots?

A Yes, but only two named slots

B No, only one named slot is allowed

C No, slots cannot be named

D Yes, with different names for each slot

Multiple named slots can be defined with unique names to allow flexible content insertion.

Which attribute is used by the parent to target a named slot?

A target

B slot

C id

D name

The parent uses the slot attribute to specify which named slot the content belongs to.

Explain how named slots work in Svelte and how a parent component uses them.

Think about how you give different parts of content to different places inside a component.

Describe a scenario where using multiple named slots in a Svelte component is helpful.

Imagine a card component with different sections.

Practice

1. What is the main purpose of named slots in Svelte components?

easy

A. To allow placing content into specific parts of a component

B. To define component styles globally

C. To handle component state changes

D. To import external JavaScript files

Solution

1. Step 1: Understand what slots do

   Slots let you insert content inside a component from outside.

2. Step 2: Identify the role of named slots

   Named slots let you put content into specific places inside the component, not just one default spot.

3. Final Answer:

   To allow placing content into specific parts of a component -> Option A

4. Quick Check:

   Named slots = specific content placement [OK]

Hint: Named slots = content in specific component areas [OK]

Common Mistakes:

• Confusing slots with styling or state
• Thinking slots import files
• Assuming slots handle events

2. Which of the following is the correct syntax to define a named slot called header inside a Svelte component?

easy

A.

B.

C.

D.

Solution

1. Step 1: Recall slot syntax in Svelte

   Svelte uses the <slot> tag with a name attribute to define named slots.

2. Step 2: Match correct attribute

   The attribute to name a slot is name, not id or custom tags.

3. Final Answer:

   <slot name="header"></slot> -> Option D

4. Quick Check:

   Named slot syntax = <slot name="..."> [OK]

Hint: Named slots use syntax [OK]

Common Mistakes:

• Using id instead of name attribute
• Using custom tags instead of <slot>
• Omitting the name attribute

3. Given this Svelte component usage:

<MyComponent>
  <div slot="title">Welcome</div>
  <div slot="footer">Goodbye</div>
</MyComponent>

And inside MyComponent.svelte you have:

<slot name="title">Default Title</slot>
<slot name="footer">Default Footer</slot>

What will be rendered in the browser?

medium

A. Default Title and Default Footer ignoring the passed content

B. Only Welcome is shown, Goodbye is ignored

C. Welcome and Goodbye in their respective slot positions

D. An error occurs because slots are not used correctly

Solution

1. Step 1: Understand slot filling

   Content with slot="title" fills the named slot "title" in the component.

2. Step 2: Match passed content to slots

   The <div slot="title">Welcome</div> replaces the default title slot content, same for footer.

3. Final Answer:

   Welcome and Goodbye in their respective slot positions -> Option C

4. Quick Check:

   Named slots filled = passed content shown [OK]

Hint: Content with slot="name" replaces default slot content [OK]

Common Mistakes:

• Thinking default slot content always shows
• Assuming only default slot works
• Confusing slot attribute usage

4. What is wrong with this usage of named slots?

<MyComponent>
  <div slot="header">Hello</div>
  <div slot="footer">Bye</div>
  <div slot="header">Again</div>
</MyComponent>

Assuming MyComponent defines named slots header and footer.

medium

A. Slots must be direct children of the component, so this is invalid

B. Multiple elements use the same slot name 'header', causing only the last to render

C. Slot names must be unique and cannot be reused in the same component usage

D. There is no error; all content will render in the header slot

Solution

1. Step 1: Check multiple slot usage

   When multiple elements use the same slot name, only the last one is rendered in that slot.

2. Step 2: Understand slot content replacement

   The first header content is replaced by the second because slots accept one content block per name.

3. Final Answer:

   Multiple elements use the same slot name 'header', causing only the last to render -> Option B

4. Quick Check:

   Duplicate slot names = last content wins [OK]

Hint: Only one content block per named slot is rendered [OK]

Common Mistakes:

• Thinking all duplicates render together
• Believing slot names must be unique globally
• Assuming nested slots behave differently

5. You want to create a Svelte component Card with named slots for header, content, and footer. You also want to provide default content for each slot if none is passed. Which code snippet correctly implements this?

hard

A. Default Header
Default Content
Default Footer

B. Default Header
Default Content
Default Footer

C.

D. Default Header
Default Content
Default Footer

Solution

1. Step 1: Use correct named slot syntax with default content

   Named slots require name attribute and default content inside the slot tags.

2. Step 2: Verify all slots have names and defaults

   Default Header Default Content Default Footer correctly names all slots and provides default text inside each slot tag.

3. Final Answer:

   <slot name="header">Default Header</slot> <slot name="content">Default Content</slot> <slot name="footer">Default Footer</slot> -> Option A

4. Quick Check:

   Named slots with defaults = <slot name="...">default</slot> [OK]

Hint: Named slots need name attribute and default content inside [OK]

Common Mistakes:

• Omitting name attribute
• Using slot attribute without value
• Mixing default slot with named slots incorrectly