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Akanksha
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Top 30 Elm Interview Questions with Answers

1. What is Elm?

a) A functional programming language
b) A JavaScript framework
c) A database management system
d) A markup language
Answer: a) A functional programming language

2. Which of the following best describes Elm's approach to handling side effects?

a) It allows side effects to happen anywhere in the code.
b) It encourages side effects to be isolated in specific parts of the code.
c) It doesn't support side effects.
d) It handles side effects automatically without developer intervention.
Answer: b) It encourages side effects to be isolated in specific parts of the code.

3. What is the Elm Architecture?

a) A design pattern for building web applications
b) A set of CSS styles
c) A JavaScript library
d) A code editor for Elm
Answer: a) A design pattern for building web applications

4. In Elm, which function is used to update the model in response to an action?

a) view
b) init
c) update
d) main
Answer: c) update

5. Which Elm function is responsible for rendering the user interface?

a) init
b) update
c) view
d) main
Answer: c) view

6. What does the Html.beginnerProgram function return in Elm?

a) An HTML element
b) A program that doesn't handle user inputs
c) A program for advanced developers
d) A beginner-friendly Elm program template
Answer: b) A program that doesn't handle user inputs

7. How does Elm enforce immutability?

a) It doesn't enforce immutability.
b) All variables are declared as mutable by default.
c) It prevents reassignment of variables after they are defined.
d) It allows reassignment but discourages it.
Answer: c) It prevents reassignment of variables after they are defined.

8. Which Elm function is used to create a list?

a) makeList
b) list
c) createList
d) Elm doesn't have a built-in list function.
Answer: b) list

9. In Elm, what is the purpose of the Html.map function?

a) To apply a function to each element in a list
b) To map an HTML element to a function
c) To convert an HTML program into an Elm model
d) To map a function over an HTML message
Answer: d) To map a function over an HTML message

10. Which Elm function is used to perform HTTP requests?

a) Http.get
b) Http.request
c) Http.send
d) Elm does not support HTTP requests.
Answer: b) Http.request

11. How can you include comments in Elm code?

a) Using the // syntax
b) Using the <!-- --> syntax
c) Elm does not support comments.
d) Using the -- syntax
Answer: d) Using the -- syntax

12. What is a port in Elm?

a) A part of an HTML page
b) A way to communicate with JavaScript
c) A type of CSS selector
d) A function that calculates a value
Answer: b) A way to communicate with JavaScript

13. Which Elm function is used to perform element updates with animation?

a) Html.animate
b) Html.transition
c) Html.keyed
d) Elm does not provide built-in animation functions.
Answer: d) Elm does not provide built-in animation functions.

14. What is the purpose of the Html.Keyed.node function in Elm?

a) To create a key for an HTML element
b) To add a node to the DOM
c) To group multiple nodes under a single key
d) Elm does not have a Html.Keyed.node function.
Answer: b) To add a node to the DOM

15. In Elm, what is the role of the Html.Keyed.unique function?

a) To generate unique keys for HTML elements
b) To check for uniqueness of HTML elements
c) To remove duplicate keys from a list of HTML elements
d) Elm does not have a Html.Keyed.unique function.
Answer: a) To generate unique keys for HTML elements

16. What is the purpose of the Platform module in Elm?

a) To create platforms for mobile applications
b) To define the structure of an Elm application
c) To manage platform-specific configurations
d) Elm does not have a Platform module.
Answer: b) To define the structure of an Elm application

17. Which Elm module is used for working with dates and times?

a) Date
b) Time
c) DateTime
d) Elm does not have built-in date and time modules.
Answer: a) Date

18. How does Elm handle error and exception reporting?

a) It displays errors in the console.
b) It crashes the application on any error.
c) It logs errors to a server.
d) Elm does not support error reporting.
Answer: a) It displays errors in the console.

19. What is the purpose of the Task module in Elm?

a) To define asynchronous tasks in Elm
b) To define CSS tasks
c) To define server-side tasks
d) Elm does not have a Task module.
Answer: a) To define asynchronous tasks in Elm

20. How does Elm handle interop with JavaScript?

a) By embedding JavaScript code directly into Elm files
b) By using ports and flags
c) Elm does not support interop with JavaScript.
d) By compiling Elm code to JavaScript and running it in a JavaScript environment
Answer: b) By using ports and flags

21. In Elm, what is the role of the Browser module?

a) To manage browser history
b) To create web browsers
c) To define browser-specific styles
d) Elm does not have a Browser module.
Answer: a) To manage browser history

22. What is the Elm Virtual DOM?

a) A lightweight version of the HTML DOM
b) A concept that doesn't exist in Elm
c) A representation of the HTML DOM used for efficient updates
d) A separate DOM for virtual reality applications
Answer: c) A representation of the HTML DOM used for efficient updates

23. What is the purpose of the Cmd.none function in Elm?

a) To create an empty command
b) To disable all commands in an Elm program
c) Elm does not have a Cmd.none function.
d) To represent a null command
Answer: a) To create an empty command

24. Which Elm function is used to combine two models into one?

a) mergeModels
b) combineModels
c) Html.map
d) Signal.merge
Answer: b) combineModels

25. How does Elm handle JavaScript interoperability security?

a) By trusting all JavaScript code by default
b) By using a secure JavaScript bridge
c) Elm does not support JavaScript interoperability.
d) By restricting the use of JavaScript to a safe subset
Answer: d) By restricting the use of JavaScript to a safe subset

26. What is Elm's approach to handling runtime exceptions?

a) It allows exceptions to crash the application.
b) It catches and handles exceptions gracefully.
c) It ignores exceptions.
d) It doesn't support exceptions.
Answer: a) It allows exceptions to crash the application.

27. Which operator is used for function composition in Elm?

a) <<
b) >>
c) |
d) &
Answer: a) <<

28. In Elm, what is the purpose of the Cmd.batch function?

a) To batch multiple commands into a single command
b) To create a batch of HTML elements
c) To define a batch process in Elm
d) Elm does not have a Cmd.batch function.
Answer: a) To batch multiple commands into a single command

29. How does Elm manage global application state?

a) By using global variables
b) Through the Model type and the update function
c) Elm does not support global state.
d) By storing state in HTML elements
Answer: b) Through the Model type and the update function

30. What is a subscription in Elm?

a) A method for subscribing to newsletters
b) A way to listen for external events and update the model
c) A type of HTML element
d) A type of CSS style
Answer: b) A way to listen for external events and update the model

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