beforeUpdate and afterUpdate in Svelte - Interactive Code Practice

Practice - 5 Tasks

1fill in blank

easy

Complete the code to import the lifecycle function that runs before the DOM updates.

Svelte

import { [1] } from 'svelte';

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

AbeforeUpdate

BafterUpdate

ConMount

DonDestroy

Attempts:

3 left

💡 Hint

Common Mistakes

Choosing 'afterUpdate' which runs after the DOM updates.

Confusing with 'onMount' which runs once when component mounts.

The beforeUpdate function runs just before the DOM updates in Svelte.

2fill in blank

medium

Complete the code to run a function after the DOM updates.

Svelte

afterUpdate(() => { [1] });

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

Aconsole.log('On mount')

Bconsole.log('Before update')

Cconsole.log('After update')

Dconsole.log('On destroy')

Attempts:

3 left

💡 Hint

Common Mistakes

Logging 'Before update' inside afterUpdate.

Using onMount or onDestroy messages here.

The function inside afterUpdate runs after the DOM has updated, so logging 'After update' fits.

3fill in blank

hard

Fix the error in the code to correctly import both lifecycle functions.

Svelte

import { [1] } from 'svelte';

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

AbeforeUpdate, afterUpdate

BafterUpdate

CbeforeUpdate

DonMount

Attempts:

3 left

💡 Hint

Common Mistakes

Choosing only one function when both are needed.

Using invalid or unrelated function names.

To correctly import both beforeUpdate and afterUpdate, use comma-separated names: beforeUpdate, afterUpdate.

4fill in blank

hard

Fill both blanks to run code before and after the DOM updates.

Svelte

import { [1], [2] } from 'svelte';

[1](() => console.log('Before update'));
[2](() => console.log('After update'));

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

AbeforeUpdate

BonMount

CafterUpdate

DonDestroy

Attempts:

3 left

💡 Hint

Common Mistakes

Mixing up beforeUpdate and afterUpdate.

Using onMount or onDestroy instead.

Use beforeUpdate to run code before DOM updates and afterUpdate to run code after DOM updates.

5fill in blank

hard

Fill all three blanks to create a Svelte component that logs messages before update, after update, and on mount.

Svelte

<script>
import { [1], [2], [3] } from 'svelte';

[1](() => console.log('Before update'));
[2](() => console.log('After update'));
[3](() => console.log('On mount'));
</script>

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

AbeforeUpdate

BafterUpdate

ConMount

DonDestroy

Attempts:

3 left

💡 Hint

Common Mistakes

Confusing the order of lifecycle functions.

Using onDestroy instead of onMount.

This component imports and uses beforeUpdate, afterUpdate, and onMount to log messages at the right lifecycle moments.