Pipe chaining in Angular - Interactive Code Practice

Practice - 5 Tasks

1fill in blank

easy

Complete the code to chain two pipes in Angular template.

Angular

<p>{{ message [1] uppercase }}</p>

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

A:

B|

C&

D||

Attempts:

3 left

💡 Hint

Common Mistakes

Using logical operators like & or || instead of the pipe symbol.

Using colon : which is for pipe parameters, not chaining.

In Angular templates, pipes are chained using the pipe symbol |.

2fill in blank

medium

Complete the code to chain 'uppercase' and 'slice' pipes to show first 5 letters in uppercase.

Angular

<p>{{ name [1] uppercase [2] slice:0:5 }}</p>

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

A:

B|

C&

D||

Attempts:

3 left

💡 Hint

Common Mistakes

Using colon : to chain pipes instead of parameters.

Using logical operators instead of pipe symbol.

Use the pipe symbol | to chain pipes. Parameters use colon :.

3fill in blank

hard

Fix the error in chaining 'date' and 'uppercase' pipes to format date and convert to uppercase.

Angular

<p>{{ today [1] date:'shortDate' [2] uppercase }}</p>

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

A|

B:

C&

D||

Attempts:

3 left

💡 Hint

Common Mistakes

Using colon : to chain pipes instead of parameters.

Using logical operators instead of pipe symbol.

Use the pipe symbol | to chain pipes. Parameters use colon :.

4fill in blank

hard

Fill both blanks to chain 'lowercase' and 'slice' pipes to show last 3 letters in lowercase.

Angular

<p>{{ word [1] lowercase [2] slice:-3 }}</p>

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

A|

B:

C&

D||

Attempts:

3 left

💡 Hint

Common Mistakes

Using colon : to chain pipes instead of parameters.

Using logical operators instead of pipe symbol.

Both blanks need the pipe symbol | to chain the pipes correctly.

5fill in blank

hard

Fill all three blanks to chain 'slice', 'uppercase', and 'replace' pipes to show first 4 letters uppercase and replace 'A' with '@'.

Angular

<p>{{ text [1] slice:0:4 [2] uppercase [3] replace:'A':'@' }}</p>

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

A|

B:

D&

Attempts:

3 left

💡 Hint

Common Mistakes

Using logical operators instead of pipe symbol.

Using colon to chain pipes instead of parameters.

Use pipe symbol | to chain pipes and colon : for parameters inside pipes.

Practice

1. What does pipe chaining in Angular templates allow you to do?

easy

A. Create multiple services at once

B. Run multiple components in sequence

C. Bind multiple events to a single element

D. Apply multiple pipes one after another to transform data

Solution

1. Step 1: Understand what pipes do in Angular

   Pipes transform data in templates to change how it looks.

2. Step 2: Understand pipe chaining

   Pipe chaining means applying several pipes in a row, where each pipe uses the previous pipe's output.

3. Final Answer:

   Apply multiple pipes one after another to transform data -> Option D

4. Quick Check:

   Pipe chaining = multiple pipes applied in sequence [OK]

Hint: Remember pipes transform data; chaining applies many in order [OK]

Common Mistakes:

• Confusing pipes with components or services
• Thinking pipes run in parallel instead of sequence
• Believing pipe chaining changes event bindings

2. Which of the following is the correct syntax for chaining pipes in an Angular template?

easy

A. {{ value | pipe1 | pipe2 }}

B. {{ value | pipe1, pipe2 }}

C. {{ value | pipe1; pipe2 }}

D. {{ value | pipe1 & pipe2 }}

Solution

1. Step 1: Recall Angular pipe chaining syntax

   Angular uses the pipe symbol | to chain pipes in templates.

2. Step 2: Identify correct chaining format

   Multiple pipes are chained by repeating | pipeName after the value.

3. Final Answer:

   {{ value | pipe1 | pipe2 }} -> Option A

4. Quick Check:

   Pipe chaining uses multiple | symbols [OK]

Hint: Use multiple | symbols to chain pipes [OK]

Common Mistakes:

• Using commas or semicolons instead of pipe symbols
• Trying to chain pipes with & or other operators
• Missing the pipe symbol between pipes

3. Given the Angular template code:
{{ 'angular' | uppercase | slice:0:3 }}
What will be the displayed output?

medium

A. ANG

B. ang

C. ANGULAR

D. angul

Solution

1. Step 1: Apply the first pipe uppercase

   The string 'angular' becomes 'ANGULAR'.

2. Step 2: Apply the second pipe slice:0:3

   Slice takes characters from index 0 up to (but not including) 3, so 'ANG'.

3. Final Answer:

   ANG -> Option A

4. Quick Check:

   Uppercase then slice = 'ANG' [OK]

Hint: Apply pipes left to right, each uses previous output [OK]

Common Mistakes:

• Applying slice before uppercase
• Confusing slice end index as inclusive
• Expecting lowercase output

4. What is wrong with this Angular template expression?
{{ 123 | uppercase | slice:0:2 }}

medium

A. Numbers cannot be used with pipes

B. There is no error; this works fine

C. The uppercase pipe cannot be applied to a number

D. The slice pipe requires a string input

Solution

1. Step 1: Check the first pipe uppercase usage

   Angular's uppercase pipe coerces the input to a string first (123 becomes '123'), then applies toUpperCase(), resulting in '123'.

2. Step 2: Apply the second pipe slice:0:2

   On '123', slice from 0 to 2 gives '12'. No error occurs.

3. Final Answer:

   There is no error; this works fine -> Option B

4. Quick Check:

   Uppercase coerces number to string, then slice works [OK]

Hint: Angular pipes like uppercase coerce non-strings to string [OK]

Common Mistakes:

• Thinking uppercase strictly requires string input without coercion
• Believing numbers cause runtime errors in pipes
• Assuming slice would fail due to input type

5. You want to display a user's name in uppercase but only show the first 5 characters. Which pipe chaining expression correctly achieves this in Angular?

hard

A. {{ userName | uppercase, slice:0:5 }}

B. {{ userName | slice:0:5 | uppercase }}

C. {{ userName | uppercase | slice:0:5 }}

D. {{ userName | slice:5 | uppercase }}

Solution

1. Step 1: Understand the desired output

   The name should be fully uppercase, then only the first 5 characters shown.

2. Step 2: Determine correct pipe order

   First apply uppercase to convert all letters, then slice:0:5 to get first 5 characters.

3. Step 3: Check options for correct syntax and order

   {{ userName | uppercase | slice:0:5 }} applies uppercase first, then slice, which matches the requirement.

4. Final Answer:

   {{ userName | uppercase | slice:0:5 }} -> Option C

5. Quick Check:

   Uppercase then slice = correct order [OK]

Hint: Uppercase first, then slice to get correct output [OK]

Common Mistakes:

• Slicing before uppercase changes output
• Using commas instead of pipes
• Wrong slice parameters