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This post lists some subjective questions and answers related to Angular Pipes. This collection contains some potential interview questions that may be helpful if you are preparing for a Frontend Engineering job interview specific to Angular framework. Check out Angular Interview Series – Topic Wise Q&A.
1. What are pipes in Angular?
Pipes are simple functions in Angular that transform data for display in templates, allowing you to format, filter, or manipulate data easily.
2. How do you use a pipe in a template?
You use a pipe in a template by appending the pipe operator (|) followed by the pipe name, e.g., {{ value | pipeName }}.
3. What is the purpose of the async pipe?
The async pipe subscribes to an observable or promise and automatically updates the view with the latest value, handling subscriptions automatically.
4. How do you create a custom pipe?
You create a custom pipe by defining a class that implements the PipeTransform interface and decorating it with @Pipe(), then providing a transform method.
5. What is the difference between pure and impure pipes?
Pure pipes only re-evaluate when their input changes, while impure pipes re-evaluate on every change detection cycle, which can impact performance.
6. Can you pass parameters to pipes?
Yes, you can pass parameters to pipes by adding them after a colon, e.g., {{ value | pipeName:parameter1:parameter2 }}.
7. What built-in pipes does Angular provide?
Angular provides several built-in pipes, including DatePipe, CurrencyPipe, DecimalPipe, PercentPipe, and JsonPipe.
8. When should you use a pipe instead of a method in a template?
You should use a pipe when you want to format data for display, as pipes are optimized for performance, while methods can lead to unnecessary re-evaluations.
9. How can you chain multiple pipes?
You can chain multiple pipes by using the pipe operator multiple times, e.g., {{ value | pipe1 | pipe2 }}.
10. Can pipes be used in component class?
Yes, you can use pipes in component class by injecting PipeTransform and using the pipe’s transform method, though it’s more common to use them in templates.
These are a few questionnaires specific to Angular Pipes. I will be adding more questions and answers to this post. To know more details please refer to the Official documentation on Angular Pipes.