Each blocks ({#each}) in Svelte - Mini Project: Build & Apply

Using Each Blocks ({#each}) in Svelte

📖 Scenario: You are building a simple webpage that shows a list of fruits you like. You want to display each fruit as a separate item on the page.

🎯 Goal: Create a Svelte component that uses the {#each} block to display a list of fruits as an unordered list.

📋 What You'll Learn

Create an array called fruits with the exact values: "Apple", "Banana", "Cherry"

Create a variable called title with the value "My Favorite Fruits"

Use a {#each} block to loop over fruits and display each fruit inside an <li> element

Add a <h2> element that shows the title above the list

💡 Why This Matters

🌍 Real World

Displaying lists of items like products, tasks, or messages is very common in web apps. Using {#each} blocks helps show these lists easily and dynamically.

💼 Career

Knowing how to use {#each} blocks in Svelte is essential for frontend developers working with Svelte to build interactive user interfaces.

1

Create the fruits array

Create an array called fruits with these exact string values: "Apple", "Banana", and "Cherry".

Svelte

// Your code here

Hint

Use let fruits = ["Apple", "Banana", "Cherry"]; inside the <script> tag.

2

Add a title variable

Add a variable called title with the exact value "My Favorite Fruits" inside the <script> tag below the fruits array.

Svelte

  let fruits = ["Apple", "Banana", "Cherry"];
  // Your code here

Hint

Declare let title = "My Favorite Fruits"; inside the <script> tag.

3

Use {#each} block to list fruits

Below the <script> tag, add an unordered list <ul>. Inside it, use a {#each} block with fruit as the item variable to loop over fruits. For each fruit, create a list item <li> that displays the fruit name.

Svelte

  let fruits = ["Apple", "Banana", "Cherry"];
  let title = "My Favorite Fruits";

Hint

Use {#each fruits as fruit} to loop and create <li>{fruit}</li> inside the <ul>.

4

Add the title heading

Above the unordered list <ul>, add a heading <h2> that displays the title variable.

Svelte

  let fruits = ["Apple", "Banana", "Cherry"];
  let title = "My Favorite Fruits";




  {#each fruits as fruit}
    {fruit}
  {/each}

Hint

Insert <h2>{title}</h2> above the <ul> block.

Practice

1. What does the {#each} block do in Svelte?

easy

A. Creates a conditional statement to show or hide content

B. Repeats a block of HTML for each item in a list

C. Defines a reusable component

D. Declares a reactive variable

Solution

1. Step 1: Understand the purpose of {#each}

   The {#each} block is used to repeat content for every item in a list or array.

2. Step 2: Compare with other options

   Options A, C, and D describe other Svelte features, not list repetition.

3. Final Answer:

   Repeats a block of HTML for each item in a list -> Option B

4. Quick Check:

   {#each} = repeat list items [OK]

Hint: Remember: {#each} loops over lists [OK]

Common Mistakes:

• Confusing {#each} with {#if}
• Thinking it creates components
• Assuming it declares variables

2. Which of the following is the correct syntax to loop over an array items and display each item in Svelte?

easy

A. {#each items to item} <p>{item}</p> {/each}

B. {#each item in items} <p>{item}</p> {/each}

C. {#each items for item} <p>{item}</p> {/each}

D. {#each items as item} <p>{item}</p> {/each}

Solution

1. Step 1: Recall Svelte each block syntax

   The correct syntax is {#each array as item} to loop over an array.

2. Step 2: Check each option

   Only {#each items as item} <p>{item}</p> {/each} uses as correctly. Options A, B, and C use incorrect keywords.

3. Final Answer:

   {#each items as item} <p>{item}</p> {/each} -> Option D

4. Quick Check:

   Use as keyword in {#each} [OK]

Hint: Use 'as' keyword: {#each array as item} [OK]

Common Mistakes:

• Using 'in' instead of 'as'
• Using 'for' or 'to' keywords
• Missing the 'as' keyword

3. Given the code:

{`


  {#each fruits as fruit, i}
    
{i}: {fruit}
  {/each}
`}

What will be the rendered output inside the <ul>?

medium

A. 0: apple1: banana2: cherry

B. apple: 0banana: 1cherry: 2

C. 1: apple2: banana3: cherry

D. fruit: applefruit: bananafruit: cherry

Solution

1. Step 1: Understand the each block variables

   The loop uses fruit for the item and i for the index starting at 0.

2. Step 2: Match output format

   Each list item shows index, colon, then fruit name, so output is 0: apple, 1: banana, 2: cherry.

3. Final Answer:

   <li>0: apple</li><li>1: banana</li><li>2: cherry</li> -> Option A

4. Quick Check:

   Index starts at 0, item after colon [OK]

Hint: Index starts at 0 in {#each items as item, i} [OK]

Common Mistakes:

• Confusing index and item order
• Starting index at 1 instead of 0
• Using wrong variable names

4. What is wrong with this Svelte code snippet?

{`


  {#each numbers as number}
    
{num}
  {/each}
`}

medium

A. The variable inside the block should be 'number', not 'num'

B. The array 'numbers' is not defined

C. The each block syntax is incorrect

D. Missing closing {/each} tag

Solution

1. Step 1: Check variable names inside each block

   The loop defines number as the item, but inside the block it uses {num}, which is undefined.

2. Step 2: Verify other syntax parts

   The array is defined, the each block syntax and closing tag are correct.

3. Final Answer:

   The variable inside the block should be 'number', not 'num' -> Option A

4. Quick Check:

   Use same variable name inside each block [OK]

Hint: Use the exact loop variable name inside the block [OK]

Common Mistakes:

• Using a different variable name inside the block
• Forgetting to close the each block
• Misnaming the array variable

5. You want to render a list of users with unique IDs and update the list efficiently when users change. Which is the best way to use {#each} with keys in Svelte?

hard

A. {#each users as user (user.name)} <p>{user.name}</p> {/each}

B. {#each users as user} <p>{user.name}</p> {/each}

C. {#each users as user (user.id)} <p>{user.name}</p> {/each}

D. {#each users as user (index)} <p>{user.name}</p> {/each}

Solution

1. Step 1: Understand keys in each blocks

   Keys help Svelte track items uniquely for efficient updates. The key should be a unique, stable identifier like user.id.

2. Step 2: Evaluate options

   {#each users as user (user.id)} <p>{user.name}</p> {/each} uses user.id as key, which is best. {#each users as user} <p>{user.name}</p> {/each} has no key, less efficient. {#each users as user (user.name)} <p>{user.name}</p> {/each} uses user.name, which may not be unique. {#each users as user (index)} <p>{user.name}</p> {/each} uses index, which can cause issues when list changes.

3. Final Answer:

   {#each users as user (user.id)} <p>{user.name}</p> {/each} -> Option C

4. Quick Check:

   Use unique ID as key in each block [OK]

Hint: Use unique IDs as keys: {#each items as item (item.id)} [OK]

Common Mistakes:

• Not using keys at all
• Using non-unique keys like names
• Using index as key causing update bugs