Angular - Interview Questions and Answers for 'Angular' | Search Interview Question

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Q31. What are the different ways we can specify the selector for the component ?

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Q32. How dependency injection in angular helps with loose coupling in angular ?

Angular

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Q33. What are the spec.ts files in angular ?

Angular

Ans. The spec files are unit tests for your source files. The convention for Angular applications is to have a .spec.ts file for each .ts file. They are run using the Jasmine javascript test framework through the Karma test runner

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Q34. What are abservables in angular ?

Angular

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Q35. Can we apply strict mode to a function ?

Angular

Ans. Yes

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Q36. Which file holds the dependent package information ?

Angular

Ans. package.json

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Q37. Have you ever faced any problem due to package version incompatibility in angular ? How did you fix it ?

Angular

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Q38. Difference between ViewChild and ContentChild.

Angular

Ans. Any directive, component, and element which is part of component template is accessed as ViewChild. Whereas, any element or component which is projected inside is accessed as ContentChild.

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Q39. Which change detection strategy do you use in your application and Why ?

Angular

Ans. We use ChangeDetectionStrategy.Push

As the application grows bigger , The default change detection strategy could become a performance overhead and hence should be avoided.

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Q40. What are the different conditions that triggers view update in case of push ChangeDetectionStrategy ?

Angular

Ans. 1. Any change in Input
2. Any even originating from the component or it's child components
3. Explicit trigger

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Q41. What is a component decorator ?

Angular

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Q42. What is interpolation in Angular ?

Angular

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Q43. Have you ever had any problem with asynchronous programming due to race condition ?

Angular

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Q44. What are the benefits of using UI framework like Angular , View js etc instead of plain vanilla js and html ?

Javascript

Ans. These frameworks facilitates easier product development and enhancement and maintainability by having separation of concerns ( using oops ) and helps in development of reusable libraries / components. So in nutshell , they make development and maintenance of large scale application easier.

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Q45. Can you please share best practices while designing an angular application ?

Angular

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Q46. How can print the whole object state in the console in javascript ?

Javascript

Ans. We can JSON.stringify

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Q47. What is the difference between closing and completing the observer / listener ?

Angular

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Q48. Have you ever faced problem because of some listener / observers / subscriber performing action on the subscription which you don't want ? How did you fix the problem ?

Angular

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Q49. What is the difference between subscribe and emit ?

Angular

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Q50. What is the difference between subscribe and unsubscribe ?

Angular

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Q51. What is the difference between Subject and Observable ?

Angular

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Q52. What does pipe does on an observable ?

RxJs

Ans. With pipe we specify the operator function to which this observable is passed for transforming the observable.

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Q53. What do we specify within the pipe method ?

RxJs

Ans. Operator function to which an observable is passed for transformation.

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Q54. Why do we do transformation on the observable itself rather than doing it in the subscriber ?

RxJs

Ans. Because that way we just need to do that transformation at one place and not within each subscriber. Single source of truth.

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Q55. Can we specify multiple functions in the pipe ? What happens if we do it ?

RxJs

Ans. Yes, We can specify multiple functions within pipe method. In that case first function get's called with the observable , the response if then passed to the second method and so on.

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Q56. Can we specify multiple maps within pipe ?

RxJs

Ans. Yes, it's same as passing multiple methods within pipe. Output of one map is passed to second and so on.

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Q57. How can we sort an observable of a user array on user name ( name being one of the field of user ) ?

RxJs

Ans. userArrayObservable.pipe(
map(userArray => {
return userArray.sort(comparator);
});
)

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Q58. What does this warning message for the unit test means

WARN: 'Spec has no expectations.'

Angular

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Q59. How can you trim all strings in an array ?

Ans. array.map(s => s.trim())

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Q60. Can we get the validators for a control in angular ? How ?

Angular

Ans. No - https://github.com/angular/angular/issues/13461

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