Interview Questions and Answers for 'A' | Search Interview Question

Interview Questions and Answers for 'A' - 3077 question(s) found - Order By Rating

Q1. What is Array.Map function ? What will be output of following ?

const myArray = [1, 4, 9, 16];
const result = myArray.map(x => x * 2);

Javascript

Ans. It will create an array with each value as x*2

[2, 8, 18, 32]

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Q2. What is systemd in Unix ?

Unix

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Q3. Why cannot we initialize a final field within the constructor if the initialization is within try block ?

Core Java

Ans. What if the initialization throws an exception. In that case , it will let it move forward without initializing the final field. So it's a way to enforce that either the field is initialized or it fails completely.

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Q4. Can we initialize final fields within the constructor ? Why ?

Core Java

Ans. Yes, Because final fields needs to be initialized before the construction of the object completes. Not necessarily at the time of class loading.

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Q5. Can we have a directive that get's applied based on an attribute on a field ?

Angular

Ans. Yes

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Q6. How can we add a particular styling to a field based on a condition ?

Angular

Ans. We can create a directive to do that.

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Q7. What is the use of ElementRef in angular ?

Angular

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Q8. What is the use of Renderer class in angular ?

Angular

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Q9. What is the use of NgControl ?

Angular

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Q10. Can we have multiple selectors for a directive in Angular ?

Angular

Ans. Yes

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Q11. How can we add a text in front of all input fields in an application ?

Angular

Ans. We can create a directive with selector as 'input' and then onInit of the directive , we can append the text to the input control html.

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Q12. 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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Q13. Is it safe to use session storage ?

Javascript

Ans. Session storage can be accessed from XSS (Cross site Scripting) attacks but cookies (if set with "HttpOnly" and "Secure" flags) are more safer against these attacks.

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Q14. How can you trim all strings in an array ?

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

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Q15. What does this warning message for the unit test means

WARN: 'Spec has no expectations.'

Angular

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Q16. Do you ever merge changes from one feature branch to another ? Why ?

SCM

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Q17. Can we do a thread specific heap allocation ?

Memory Management

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Q18. What resources are shared between threads ?

Threads

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Q19. Do threads have a distinct heap ?

Memory Management

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Q20. 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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Q21. 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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Q22. 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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Q23. 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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Q24. What do we specify within the pipe method ?

RxJs

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

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Q25. 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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Q26. What is the difference between Subject and Observable ?

Angular

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Q27. What is the difference between subscribe and unsubscribe ?

Angular

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Q28. What is the difference between subscribe and emit ?

Angular

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Q29. 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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Q30. What is the difference between closing and completing the observer / listener ?

Angular

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