Auto-subscription with $ prefix in Svelte - Interactive Code Practice

Practice - 5 Tasks

1fill in blank

easy

Complete the code to auto-subscribe to the store and display its value.

Svelte

<script>
  import { writable } from 'svelte/store';
  const count = writable(0);
</script>
<p>Count: {{$ [1] }}</p>

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

Aget

Bsubscribe

Ccount

Dset

Attempts:

3 left

💡 Hint

Common Mistakes

Using the store variable without $ prefix, which won't auto-subscribe.

Trying to call subscribe() manually inside the template.

Using $count auto-subscribes to the store and updates the value reactively.

2fill in blank

medium

Complete the code to update the store value on button click using auto-subscription.

Svelte

<script>
  import { writable } from 'svelte/store';
  const count = writable(0);
  function increment() {
    count.[1](n => n + 1);
  }
</script>
<button on:click={increment}>Increment</button>
<p>Count: {$count}</p>

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

Aset

Bupdate

Csubscribe

Dget

Attempts:

3 left

💡 Hint

Common Mistakes

Using set without the new value.

Trying to use subscribe to change the value.

The update method lets you change the store value based on its current value.

3fill in blank

hard

Fix the error in the code to correctly auto-subscribe to the store value.

Svelte

<script>
  import { writable } from 'svelte/store';
  const name = writable('Alice');
</script>
<p>Hello, {{$ [1] }}</p>

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

Aname

B$name

Cname()

Dsubscribe

Attempts:

3 left

💡 Hint

Common Mistakes

Adding an extra $ prefix causing syntax errors.

Trying to call the store as a function.

Inside the template, use $name without extra $ or parentheses. The code already has $ before the blank, so just put name.

4fill in blank

hard

Fill both blanks to create a derived store and auto-subscribe to its value.

Svelte

<script>
  import { writable, derived } from 'svelte/store';
  const a = writable(2);
  const b = writable(3);
  const sum = derived([a, b], ([$a, $b]) => $a [1] $b);
</script>
<p>Sum: {{$ [2] }}</p>

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

A+

Bsum

C-

Da

Attempts:

3 left

💡 Hint

Common Mistakes

Using subtraction instead of addition.

Trying to use one of the original stores instead of the derived store.

The derived store sum adds $a and $b. Use sum with $ prefix to auto-subscribe.

5fill in blank

hard

Fill all three blanks to create a reactive statement that logs the store value whenever it changes.

Svelte

<script>
  import { writable } from 'svelte/store';
  const score = writable(0);

  $: console.log([1]); // logs the current score

  function increase() {
    score.[2](n => n + 1);
  }
</script>
<button on:click={increase}>Increase</button>
<p>Score: {{$ [3] }}</p>

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

A$score

Bupdate

Cscore

Dset

Attempts:

3 left

💡 Hint

Common Mistakes

Using set instead of update for incrementing.

Not using $ prefix in reactive statements causing no reactivity.

The reactive statement uses $score to auto-subscribe and log changes. The update method changes the store value. The template uses $score to display the current value, but since the $ is already in the code, just put score.