getContext in Svelte - Interactive Code Practice

Practice - 5 Tasks

1fill in blank

easy

Complete the code to get a context value inside a Svelte component.

Svelte

import { getContext } from 'svelte';

const value = getContext([1]);

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

A'myKey'

BsetContext

Ccontext

DuseContext

Attempts:

3 left

💡 Hint

Common Mistakes

Passing a function or variable instead of a string key.

Using setContext instead of getContext.

In Svelte, getContext takes a key string to retrieve the context value.

2fill in blank

medium

Complete the code to import the correct function to retrieve context in Svelte.

Svelte

import { [1] } from 'svelte';

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

AsetContext

BcreateContext

CuseContext

DgetContext

Attempts:

3 left

💡 Hint

Common Mistakes

Confusing getContext with setContext.

Using React-like functions such as useContext.

The getContext function is imported from 'svelte' to access context values.

3fill in blank

hard

Fix the error in this code that tries to get context but uses the wrong key.

Svelte

const theme = getContext([1]);

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

A'Theme'

Btheme

C'theme'

DgetContext

Attempts:

3 left

💡 Hint

Common Mistakes

Using a variable instead of a string key.

Wrong capitalization of the key string.

The key must be a string matching exactly the one used in setContext, including case.

4fill in blank

hard

Fill both blanks to get a context value and log it in a Svelte component.

Svelte

import { [1] } from 'svelte';

const data = [2]('userData');
console.log(data);

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

AgetContext

BsetContext

DuseContext

Attempts:

3 left

💡 Hint

Common Mistakes

Using setContext instead of getContext.

Not importing getContext before using it.

You import getContext and call it with the key string to retrieve context.

5fill in blank

hard

Fill all three blanks to get a context value and use it in a reactive statement.

Svelte

import { [1] } from 'svelte';

const count = [2]('countKey');

$: doubled = count [3] 2;

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

AgetContext

C*

D+

Attempts:

3 left

💡 Hint

Common Mistakes

Using + instead of * for multiplication.

Not importing getContext before use.

Import and call getContext to get the value, then multiply it by 2 reactively.

Practice

1. What is the main purpose of getContext in Svelte?

easy

A. To access data provided by a parent component without passing props

B. To create a new reactive variable inside a component

C. To define a component's local state

D. To listen for DOM events inside a component

Solution

1. Step 1: Understand the role of getContext

   getContext is used to access data that a parent component has shared using setContext.

2. Step 2: Compare with other options

   Other options describe unrelated tasks like local state or event listening, which getContext does not do.

3. Final Answer:

   To access data provided by a parent component without passing props -> Option A

4. Quick Check:

   getContext accesses parent data = B [OK]

Hint: Remember: getContext reads shared parent data [OK]

Common Mistakes:

• Confusing getContext with local state creation
• Thinking getContext listens to events
• Assuming getContext sets data instead of getting

2. Which of the following is the correct syntax to retrieve a context value with key 'user' in a Svelte component?

easy

A. const user = getContext({ key: 'user' });

B. const user = getContext('user');

C. const user = getContext(user);

D. const user = setContext('user');

Solution

1. Step 1: Recall getContext syntax

   getContext takes a string key to retrieve the shared value.

2. Step 2: Analyze options

   const user = getContext('user'); uses the correct string key syntax. const user = setContext('user'); wrongly uses setContext. const user = getContext(user); passes a variable instead of a string. const user = getContext({ key: 'user' }); passes an object, which is invalid.

3. Final Answer:

   const user = getContext('user'); -> Option B

4. Quick Check:

   getContext('key') syntax = D [OK]

Hint: Use string keys in quotes with getContext [OK]

Common Mistakes:

• Using setContext instead of getContext
• Passing variables or objects instead of string keys
• Missing quotes around the key

3. Given the parent component sets context with setContext('theme', 'dark'), what will the child component log with console.log(getContext('theme'))?

medium

A. 'dark'

B. 'light'

C. undefined

D. null

Solution

1. Step 1: Understand setContext and getContext relation

   The parent sets the key 'theme' with value 'dark'. The child uses getContext with the same key.

2. Step 2: Determine the logged value

   Since the keys match, getContext returns 'dark'. Other options are incorrect values or undefined.

3. Final Answer:

   'dark' -> Option A

4. Quick Check:

   Matching keys return set value = A [OK]

Hint: Matching keys return parent's setContext value [OK]

Common Mistakes:

• Expecting default or unrelated values
• Using different keys causing undefined
• Confusing setContext and getContext roles

4. What is the error in this child component code snippet?

const data = getContext();

medium

A. getContext must be imported from 'svelte/store'

B. getContext cannot be used in child components

C. getContext requires two arguments

D. Missing key argument in getContext call

Solution

1. Step 1: Check getContext usage

   getContext requires a key argument to specify which context to retrieve.

2. Step 2: Evaluate the code snippet

   The snippet calls getContext without any argument, causing an error.

3. Final Answer:

   Missing key argument in getContext call -> Option D

4. Quick Check:

   getContext needs a key argument = A [OK]

Hint: Always pass a key string to getContext [OK]

Common Mistakes:

• Calling getContext without arguments
• Thinking getContext needs two arguments
• Importing getContext from wrong module

5. In a nested component structure, if a grandchild calls getContext('settings') but only the grandparent used setContext('settings', {mode: 'auto'}), what will the grandchild receive?

hard

A. An error because only the direct parent can provide context

B. undefined because context is not passed through intermediate components

C. The object {mode: 'auto'} from the grandparent

D. An empty object {} because context resets at each level

Solution

1. Step 1: Understand context propagation in Svelte

   Context set by any ancestor is accessible by all descendants, not just direct children.

2. Step 2: Apply to the nested structure

   The grandchild can access the 'settings' context set by the grandparent, receiving the object {mode: 'auto'}.

3. Final Answer:

   The object {mode: 'auto'} from the grandparent -> Option C

4. Quick Check:

   Context flows down all descendants = C [OK]

Hint: Context flows down all descendants, not just direct children [OK]

Common Mistakes:

• Thinking only direct parent context is accessible
• Expecting undefined if intermediate components don't set context
• Assuming context resets at each component level