Dynamic route parameters in Svelte - Interactive Code Practice

Practice - 5 Tasks

1fill in blank

easy

Complete the code to define a dynamic route parameter in SvelteKit.

Svelte

<script>
  export let [1];
</script>

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

Aid

Bslug

Croute

Dparams

Attempts:

3 left

💡 Hint

Common Mistakes

Using a parameter name that does not match the filename segment.

Trying to access route parameters without exporting them.

In SvelteKit, dynamic route parameters are passed as props with the same name as the parameter. Here, id matches the dynamic segment in the filename.

2fill in blank

medium

Complete the code to display the dynamic parameter value inside the component.

Svelte

<script>
  export let id;
</script>

<p>Item ID: [1]</p>

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

A{id}

B$id

Cid

D{{id}}

Attempts:

3 left

💡 Hint

Common Mistakes

Writing the variable name without curly braces.

Using double curly braces like in some other frameworks.

In Svelte, to display a variable's value in HTML, you wrap it in curly braces like {id}.

3fill in blank

hard

Fix the error in the route filename to correctly capture a dynamic parameter.

Svelte

src/routes/[1].svelte

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

A<id>

B{id}

C(id)

D[id]

Attempts:

3 left

💡 Hint

Common Mistakes

Using curly braces or parentheses instead of square brackets.

Not matching the parameter name with the exported prop.

SvelteKit uses square brackets around the filename to define dynamic route parameters, like [id].svelte.

4fill in blank

hard

Fill both blanks to create a nested dynamic route and access its parameters.

Svelte

<script>
  export let [1];
  export let [2];
</script>

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

Acategory

Bpost

Cslug

Did

Attempts:

3 left

💡 Hint

Common Mistakes

Exporting parameters that don't match the route segments.

Forgetting to export one of the parameters.

For nested dynamic routes like [category]/[slug].svelte, you export both parameters category and slug.

5fill in blank

hard

Fill all three blanks to create a dynamic route and display all parameters in the component.

Svelte

<script>
  export let [1];
  export let [2];
  export let [3];
</script>

<p>Category: {category}</p>
<p>Post: {post}</p>
<p>Comment ID: {commentId}</p>

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

Acategory

Bpost

CcommentId

Dslug

Attempts:

3 left

💡 Hint

Common Mistakes

Not exporting all parameters.

Using wrong parameter names that don't match the route.

For a route like [category]/[post]/[commentId].svelte, export all three parameters to use them inside the component.

Practice

1. What does a filename like [id].svelte represent in a SvelteKit project?

easy

A. A dynamic route where id is a variable part of the URL

B. A static page named literally 'id'

C. A component that cannot be accessed via URL

D. A special file for global styles

Solution

1. Step 1: Understand filename brackets in SvelteKit

   Square brackets in filenames define dynamic segments in routes, meaning the part inside brackets is a variable.

2. Step 2: Interpret [id].svelte

   This means the page matches URLs like /123 or /abc, where id changes dynamically.

3. Final Answer:

   A dynamic route where id is a variable part of the URL -> Option A

4. Quick Check:

   Filename with brackets = dynamic route [OK]

Hint: Brackets in filename mean dynamic URL part [OK]

Common Mistakes:

• Thinking bracket means static filename
• Confusing dynamic route with component name
• Assuming it is for styles or scripts

2. Which is the correct way to access a dynamic route parameter named slug inside a SvelteKit page component?

easy

A. Using export let params; in the script

B. Using window.slug in the script

C. Using const { slug } = params; inside load function

D. Using this.slug in the component

Solution

1. Step 1: Recall how SvelteKit passes route params

   Dynamic route parameters are passed to the page component as a params prop object.

2. Step 2: Declare the prop in the script

   Inside the page component (+page.svelte) script, use export let params; to receive it, then access params.slug.

3. Final Answer:

   Using export let params; in the script -> Option A

4. Quick Check:

   export let params; receives route params [OK]

Hint: export let params; in page script [OK]

Common Mistakes:

• Using export let slug; (wrong prop name)
• Accessing params from window or this
• Confusing with load function params

3. Given a file named src/routes/blog/[postId].svelte with this code:

  <script>
    export let params;
  </script>

  <h1>Post ID: {params.postId}</h1>

What will be rendered when visiting /blog/42?

medium

A. Post ID: postId

B. Post ID: 42

C. Post ID: {params.postId}

D. Error: params is undefined

Solution

1. Step 1: Understand dynamic route parameter passing

   The [postId].svelte file captures the URL segment after /blog/ as postId and passes it as params.postId.

2. Step 2: Check how params is used in the component

   The component uses {params.postId} inside the heading, so it will display the actual value from the URL.

3. Final Answer:

   <h1>Post ID: 42</h1> -> Option B

4. Quick Check:

   Dynamic param value shown = 42 [OK]

Hint: Dynamic param in URL shows inside {params.paramName} [OK]

Common Mistakes:

• Expecting literal string 'postId' instead of value
• Forgetting to export params
• Using params without export or load

4. You have a dynamic route file [user].svelte but when you visit /john, you get an error: params is undefined. What is the likely cause?

medium

A. You must use window.params to access parameters

B. You named the file incorrectly; it should be {user}.svelte

C. You forgot to export let params in the script

D. Dynamic routes do not support parameters

Solution

1. Step 1: Check how params are accessed in SvelteKit

   Dynamic route parameters are passed as a prop named params which must be exported in the script.

2. Step 2: Identify missing export

   If let params is not exported, the component cannot access it, causing params is undefined.

3. Final Answer:

   You forgot to export let params in the script -> Option C

4. Quick Check:

   Export params to access dynamic route data [OK]

Hint: Always export let params to use route parameters [OK]

Common Mistakes:

• Using curly braces in filename instead of brackets
• Trying to access params from window object
• Assuming dynamic routes don't pass params

5. You want to create a nested dynamic route in SvelteKit to show a user's post detail at URL /user/123/post/456. Which file structure and parameter access is correct?

hard

A. Files: src/routes/user/[userId]/post.svelteAccess: params.userId only

B. Files: src/routes/user/[userId]/post/[postId].svelteAccess: params.user and params.post

C. Files: src/routes/user/post/[postId].svelteAccess: params.userId and params.postId

D. Files: src/routes/user/[userId]/post/[postId].svelteAccess: params.userId and params.postId

Solution

1. Step 1: Understand nested dynamic routes in SvelteKit

   To match URL segments like /user/123/post/456, you create nested folders with dynamic filenames for each variable part.

2. Step 2: Confirm file structure and parameter names

   The correct structure is user/[userId]/post/[postId].svelte, and inside the component, you access params.userId and params.postId.

3. Final Answer:

   Files: src/routes/user/[userId]/post/[postId].svelte and access params.userId and params.postId -> Option D

4. Quick Check:

   Nested dynamic folders match URL segments [OK]

Hint: Use nested folders with brackets for each dynamic segment [OK]

Common Mistakes:

• Using wrong param names inside params object
• Missing nested folder for second dynamic segment
• Trying to access params not defined by filename