Query parameters and fragments in Angular - Interactive Code Practice

Practice - 5 Tasks

1fill in blank

easy

Complete the code to navigate with query parameters in Angular.

Angular

this.router.navigate(['/search'], { queryParams: [1] });

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

A'term=angular'

B{ term: 'angular' }

C[ term: 'angular' ]

Dterm=angular

Attempts:

3 left

💡 Hint

Common Mistakes

Passing query parameters as a string instead of an object.

Using array syntax instead of object syntax.

Query parameters must be passed as an object inside queryParams.

2fill in blank

medium

Complete the code to read query parameters using Angular's ActivatedRoute.

Angular

this.route.queryParams.subscribe(params => { this.searchTerm = params[1]; });

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

A.term

B['term']

C[term]

D('term')

Attempts:

3 left

💡 Hint

Common Mistakes

Using bracket notation with strings instead of dot notation.

Using parentheses which is invalid syntax.

You access query parameters as properties of the params object using dot notation.

3fill in blank

hard

Fix the error in the code to navigate with a fragment in Angular.

Angular

this.router.navigate(['/details'], { [1]: 'section2' });

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

Afragment

Bhash

Cfragments

DqueryParams

Attempts:

3 left

💡 Hint

Common Mistakes

Using 'fragments' or 'hash' which are not valid properties.

Confusing fragment with queryParams.

The correct property to set a URL fragment is fragment.

4fill in blank

hard

Fill both blanks to read query parameters and fragment from ActivatedRoute.

Angular

this.route.queryParams.subscribe(params => { this.id = params[1]; });
this.route.[2].subscribe(fragment => { this.section = fragment; });

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

A.id

Bfragment

Cfragments

DqueryFragment

Attempts:

3 left

💡 Hint

Common Mistakes

Using incorrect property names like 'fragments' or 'queryFragment'.

Using bracket notation for params instead of dot notation.

Query parameters are accessed with params.id and fragments with route.fragment.

5fill in blank

hard

Fill all three blanks to navigate with query parameters and a fragment.

Angular

this.router.navigate([[1]], { queryParams: [2], [3]: 'top' });

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

A'profile'

B{ user: '123' }

Cfragment

D'dashboard'

Attempts:

3 left

💡 Hint

Common Mistakes

Passing route as a string instead of an array.

Using wrong property name for fragment.

Passing queryParams as a string.

The first argument is the route array, queryParams is an object, and fragment is set with the 'fragment' property.

Practice

1. In Angular, what is the main purpose of query parameters in a URL?

easy

A. To style the page dynamically

B. To define the main route path

C. To specify the component to load

D. To pass extra information to the route without changing the path

Solution

1. Step 1: Understand URL structure

   Query parameters come after a question mark (?) in URLs and carry extra data.

2. Step 2: Role in Angular routing

   Angular uses query parameters to pass optional info without changing the main route path.

3. Final Answer:

   To pass extra information to the route without changing the path -> Option D

4. Quick Check:

   Query parameters = extra info in URL [OK]

Hint: Query parameters come after ? and don't change the route path [OK]

Common Mistakes:

• Confusing query parameters with route parameters
• Thinking query parameters change the route path
• Mixing fragments with query parameters

2. Which Angular Router method is used to navigate to a route with query parameters?

easy

A. router.navigate(['/path'], { queryParams: { key: 'value' } })

B. router.go(['/path'], { params: { key: 'value' } })

C. router.route(['/path'], { query: { key: 'value' } })

D. router.change(['/path'], { queryParams: { key: 'value' } })

Solution

1. Step 1: Recall Angular Router navigation syntax

   The correct method is navigate with an array for the path and an options object.

2. Step 2: Identify correct query parameter option

   The option to pass query parameters is queryParams, not params or query.

3. Final Answer:

   router.navigate(['/path'], { queryParams: { key: 'value' } }) -> Option A

4. Quick Check:

   Use navigate() with queryParams [OK]

Hint: Use navigate() with queryParams option to add query parameters [OK]

Common Mistakes:

• Using wrong method like go() or change()
• Passing query parameters as params or query instead of queryParams
• Not wrapping path in an array

3. Given this Angular code snippet, what will be logged?

this.route.queryParams.subscribe(params => console.log(params['page']))
this.router.navigate(['/items'], { queryParams: { page: 3 } })

medium

A. Error

B. 3

C. null

D. undefined

Solution

1. Step 1: Understand queryParams subscription

   The subscription listens for query parameter changes and logs the 'page' value.

2. Step 2: Navigate with queryParams

   The navigate call sets queryParams with page: 3, triggering the subscription.

3. Final Answer:

   3 -> Option B

4. Quick Check:

   queryParams['page'] logs 3 after navigation [OK]

Hint: queryParams subscription logs updated values after navigate [OK]

Common Mistakes:

• Expecting undefined because of timing
• Confusing queryParams with route params
• Not subscribing to queryParams observable

4. What is wrong with this Angular code to read the URL fragment?

this.route.fragment.subscribe(fragment => {
  console.log(fragment.toUpperCase())
})

medium

A. subscribe() is not a function on fragment

B. fragment is always empty string, so toUpperCase() does nothing

C. fragment can be null, so calling toUpperCase() may cause error

D. You must use queryParams to get fragment

Solution

1. Step 1: Understand fragment observable behavior

   The fragment can be null if no fragment exists in the URL.

2. Step 2: Identify risk of calling toUpperCase()

   Calling toUpperCase() on null causes a runtime error.

3. Final Answer:

   fragment can be null, so calling toUpperCase() may cause error -> Option C

4. Quick Check:

   Check for null before using string methods on fragment [OK]

Hint: Check fragment for null before string methods [OK]

Common Mistakes:

• Assuming fragment is always a string
• Trying to get fragment from queryParams
• Not subscribing to fragment observable

5. You want to navigate to '/profile' with query parameters { tab: 'settings' } and fragment 'section2'. Which code correctly does this in Angular?

hard

A. this.router.navigate(['/profile'], { queryParams: { tab: 'settings' }, fragment: 'section2' })

B. this.router.navigate(['/profile'], { params: { tab: 'settings' }, hash: 'section2' })

C. this.router.navigate(['/profile'], { query: { tab: 'settings' }, fragment: 'section2' })

D. this.router.navigate(['/profile'], { queryParams: { tab: 'settings' }, hash: 'section2' })

Solution

1. Step 1: Recall correct options for navigate()

   Angular uses queryParams for query parameters and fragment for URL fragment.

2. Step 2: Check option correctness

   this.router.navigate(['/profile'], { queryParams: { tab: 'settings' }, fragment: 'section2' }) uses correct keys: queryParams and fragment. Others use incorrect keys like params, query, or hash.

3. Final Answer:

   this.router.navigate(['/profile'], { queryParams: { tab: 'settings' }, fragment: 'section2' }) -> Option A

4. Quick Check:

   Use queryParams and fragment keys in navigate() [OK]

Hint: Use queryParams and fragment keys in navigate() options [OK]

Common Mistakes:

• Using params or query instead of queryParams
• Using hash instead of fragment
• Not passing path as array