Svelte vs React vs Vue comparison - Interactive Practice

Practice - 5 Tasks

1fill in blank

easy

Complete the code to create a reactive variable in Svelte.

Svelte

let count = 0;

function increment() {
  [1];
}

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

Acount++

Bcount += 1

Cthis.setState({ count: count + 1 })

DsetCount(count + 1)

Attempts:

3 left

💡 Hint

Common Mistakes

Using React's setState or hooks syntax in Svelte.

Trying to use this.setState which is not valid in Svelte.

In Svelte, you update reactive variables directly by assignment, like count += 1.

2fill in blank

medium

Complete the code to bind an input value to a variable in Svelte.

Svelte

<input type="text" [1]={name} />
<p>Hello, {name}!</p>

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

Abind:value

Bvalue

Con:input

Dbind:input

Attempts:

3 left

💡 Hint

Common Mistakes

Using React's controlled input pattern with onChange.

Using incorrect binding syntax like bind:input.

Svelte uses bind:value to create two-way binding between input and variable.

3fill in blank

hard

Fix the error in the Svelte component to conditionally show a message.

Svelte

{#if [1]
  <p>Welcome back!</p>
{/if}

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

AisLoggedIn

BisLoggedIn()

Cthis.isLoggedIn

DisLoggedIn === true

Attempts:

3 left

💡 Hint

Common Mistakes

Calling the variable as a function like isLoggedIn().

Using 'this' keyword which is not used in Svelte templates.

In Svelte, you use the variable name directly in the {#if} block without calling it as a function or using this.

4fill in blank

hard

Fill both blanks to create a reactive statement that updates doubled when count changes.

Svelte

<script>
  let count = 0;
  let doubled;

  $: [1] = [2] * 2;
</script>

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

Adoubled

Bcount

Ccount + 1

Ddoubled + 1

Attempts:

3 left

💡 Hint

Common Mistakes

Using expressions like count + 1 instead of count.

Trying to update the wrong variable on the left side.

The reactive statement uses $: doubled = count * 2; to update doubled whenever count changes.

5fill in blank

hard

Fill all three blanks to create a Svelte component that loops over items and shows their names.

Svelte

<script>
  let items = [
    { id: 1, name: 'Apple' },
    { id: 2, name: 'Banana' },
    { id: 3, name: 'Cherry' }
  ];
</script>

<ul>
  {#each [1] as [2] ([3])}
    <li>{item.name}</li>
  {/each}
</ul>

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

Aitems

Bitem

Citem.id

DitemsList

Attempts:

3 left

💡 Hint

Common Mistakes

Using a wrong variable name for the array or item.

Omitting the key or using an invalid key.

The {#each} block loops over items as item using item.id as a key.

Practice

1. Which framework compiles your code to efficient JavaScript at build time, reducing runtime overhead?

easy

A. Svelte

B. React

C. Vue

D. Angular

Solution

1. Step 1: Understand Svelte's compilation approach

   Svelte compiles components to optimized JavaScript during build, so no virtual DOM at runtime.

2. Step 2: Compare with React and Vue runtime behavior

   React and Vue use virtual DOM diffing at runtime, adding overhead compared to Svelte.

3. Final Answer:

   Svelte -> Option A

4. Quick Check:

   Compile-time optimization = Svelte [OK]

Hint: Svelte compiles away framework code before running [OK]

Common Mistakes:

• Thinking React compiles away virtual DOM
• Confusing Vue's runtime with compile-time
• Assuming Angular behaves like Svelte

2. Which syntax is correct for creating a reactive variable in Svelte?

easy

A. var count = 0; function doubled() { return count * 2; }

B. const [count, setCount] = useState(0);

C. data() { return { count: 0 } }

D. let count = 0; $: doubled = count * 2;

Solution

1. Step 1: Identify Svelte reactive syntax

   Svelte uses $: label to declare reactive statements that update when dependencies change.

2. Step 2: Check other options for framework syntax

   const [count, setCount] = useState(0); is React useState, C is Vue data option, D is plain JS function.

3. Final Answer:

   let count = 0; $: doubled = count * 2; -> Option D

4. Quick Check:

   Svelte reactive label = $: [OK]

Hint: Svelte uses $: for reactive declarations [OK]

Common Mistakes:

• Using React or Vue syntax in Svelte
• Forgetting the $: label for reactivity
• Using var instead of let/const in Svelte

3. Given this Svelte code snippet, what will be displayed when count is 3?

 <script>
  let count = 3;
  $: doubled = count * 2;
</script>
<p>Doubled: {doubled}</p>

medium

A. Doubled: 3

B. Doubled: 9

C. Doubled: 6

D. Doubled: undefined

Solution

1. Step 1: Calculate doubled value

   With count = 3, doubled = 3 * 2 = 6.

2. Step 2: Understand Svelte reactive update

   The reactive statement updates doubled automatically, so the displayed value is 6.

3. Final Answer:

   Doubled: 6 -> Option C

4. Quick Check:

   count * 2 = 6 [OK]

Hint: Multiply count by 2 for doubled value [OK]

Common Mistakes:

• Confusing doubled with count
• Assuming doubled is undefined without initialization
• Multiplying incorrectly

4. Identify the error in this React code compared to Svelte's approach:

function Counter() {
  let count = 0;
  function increment() {
    count++;
  }
  return <button onClick={increment}>{count}</button>;
}

medium

A. count should be declared with const in React

B. React state must use useState hook, not a plain variable

C. Svelte requires on:click instead of onClick

D. React buttons cannot display variables

Solution

1. Step 1: Check React state management

   React requires useState hook to track state changes and trigger re-render.

2. Step 2: Identify why plain variable fails

   Using let count = 0 won't update UI on increment because React doesn't track it.

3. Final Answer:

   React state must use useState hook, not a plain variable -> Option B

4. Quick Check:

   React state needs useState [OK]

Hint: React state needs useState hook, not plain variables [OK]

Common Mistakes:

• Thinking onClick is invalid in React
• Using const for mutable state
• Believing React buttons can't show variables

5. You want to build a small interactive widget with minimal setup and fast load time. Which framework is best suited and why?

hard

A. Svelte, because it compiles to minimal JavaScript and runs fast

B. Vue, because it is easy to learn and has good tooling

C. React, because of its large ecosystem and flexibility

D. Angular, because it provides a full-featured framework

Solution

1. Step 1: Analyze requirements for minimal setup and fast load

   Minimal setup and fast load favor frameworks that produce small, efficient code.

2. Step 2: Compare frameworks on output size and runtime speed

   Svelte compiles away framework code, resulting in smaller bundles and faster startup than React or Vue.

3. Step 3: Consider ecosystem and complexity

   React and Vue have bigger ecosystems but more runtime overhead; Angular is heavier and more complex.

4. Final Answer:

   Svelte, because it compiles to minimal JavaScript and runs fast -> Option A

5. Quick Check:

   Minimal setup + speed = Svelte [OK]

Hint: Small, fast widget? Choose Svelte for minimal code [OK]

Common Mistakes:

• Picking React for minimal setup despite larger runtime
• Choosing Angular for small widgets
• Ignoring compile-time benefits of Svelte