Javascript - Skill Assignment Quiz

Q1. Which operator returns true if the two compared values are not equal?

  • <>
  • ~
  • ==!
  • !==

Q2. How is a forEach statement different from a for statement?

  • Only a for statement uses a callback function.
  • A for statement is generic, but a forEach statement can be used only with an array.
  • Only a forEach statement lets you specify your own iterator.
  • A forEach statement is generic, but a for statement can be used only with an array.

Q3. Which statement is the correct way to create a variable called rate and assign it the value 100?

  • let rate = 100;
  • let 100 = rate;
  • 100 = let rate;
  • rate = 100;

Q4. Which statement creates a new object using the Person constructor? Which statement creates a new Person object called "student"?

  • var student = new Person();
  • var student = construct Person;
  • var student = Person();
  • var student = construct Person();

Q5. How does a function create a closure?

  • It reloads the document whenever the value changes.
  • It returns a reference to a variable in its parent scope.
  • It completes execution without returning.
  • It copies a local variable to the global scope.

Q6. When would you use a conditional statement?

  • When you want to reuse a set of statements multiple times.
  • When you want your code to choose between multiple options.
  • When you want to group data together.
  • When you want to loop through a group of statement.

Q7. Which Object method returns an iterable that can be used to iterate over the properties of an object?

  • Object.get()
  • Object.loop()
  • Object.each()
  • Object.keys()

Q8. What is one difference between collections created with Map and collections created with Object?

  • You can iterate over values in a Map in their insertion order.
  • You can count the records in a Map with a single method call.
  • Keys in Maps can be strings.
  • You can access values in a Map without iterating over the whole collection.

Q9. 0 && hi

  • ReferenceError
  • true
  • 0
  • false

 

Q10. Which of the following operators can be used to do a short-circuit evaluation?

  • ++
  • --
  • ==
  • ||

 

Q11. Which statement sets the Person constructor as the parent of the Student constructor in the prototype chain?

  • Student.parent = Person;
  • Student.prototype = new Person();
  • Student.prototype = Person;
  • Student.prototype = Person();

Q12. Why would you include a "use strict" statement in a JavaScript file?

  • to tell parsers to interpret your JavaScript syntax loosely
  • to tell parsers to enforce all JavaScript syntax rules when processing your code
  • to instruct the browser to automatically fix any errors it finds in the code
  • to enable ES6 features in your code

Q13. Which Variable-defining keyword allows its variable to be accessed (as undefined) before the line that defines it?

  • all of them
  • const
  • var
  • let

Q14. Which of the following values is not a Boolean false?

  • Boolean(0)
  • Boolean("")
  • Boolean(NaN)
  • Boolean("false")

Q15. Which of the following is not a keyword in JavaScript?

  • this
  • catch
  • function
  • array

Q16. Which variable is an implicit parameter for every function in JavaScript?

  • Arguments
  • args
  • argsArray
  • argumentsList

Q17. Why is it usually better to work with Objects instead of Arrays to store a collection of records?

  • Objects are more efficient in terms of storage.
  • Adding a record to an object is significantly faster than pushing a record into an array.
  • Most operations involve looking up a record, and objects can do that better than arrays.
  • Working with objects makes the code more readable.

Q18. Which statement is true about the "async" attribute for the HTML script tag?

  • It can be used for both internal and external JavaScript code.
  • It can be used only for internal JavaScript code.
  • It can be used only for internal or external JavaScript code that exports a promise.
  • It can be used only for external JavaScript code.

Q19. How do you import the lodash library making it top-level Api available as the "_" variable?

  • import _ from 'lodash';
  • import 'lodash' as _;
  • import '_' from 'lodash;
  • import lodash as _ from 'lodash';

Q20. What type of function can have its execution suspended and then resumed at a later point?

  • Generator function
  • Arrow function
  • Async/ Await function
  • Promise function

Q21. Your code is producing the error: TypeError: Cannot read property 'reduce' of undefined. What does that mean?

  • You are calling a method named reduce on an object that's declared but has no value.
  • You are calling a method named reduce on an object that does not exist.
  • You are calling a method named reduce on an empty array.
  • You are calling a method named reduce on an object that's has a null value.

Q22. Which choice is not a unary operator?

  • typeof
  • delete
  • instanceof
  • void

Q23. Which keyword is used to create an error?

  • throw
  • exception
  • catch
  • error

Q24. Which collection object allows unique value to be inserted only once?

  • Object
  • Set
  • Array
  • Map

Q23. How does the for Each() method differ from a FOR statement?

  • forEach allows you to specify your own iterator, whereas for does not.
  • forEach can be used only with strings, whereas for can be used with additional data types.
  • forEach can be used only with an array, whereas for can be used with additional data types.
  • for loops can be nested; whereas forEach loops cannot.

Q24. Which choice is an incorrect way to define an arrow function that returns an empty object?

  • => ({})
  • => {}
  • => { return {};}
  • => (({}))

Q25. Which expression evaluates to true?

  • [3] == [3]
  • 3 == '3'
  • 3 != '3'
  • 3 === '3'

Q26. Which method cancels event default behavior?

  • cancel()
  • stop()
  • preventDefault()
  • prevent()

Q27. Which method do you use to attach one DOM node to another?

  • attachNode()
  • getNode()
  • querySelector()
  • appendChild()

Q28. Which choice is a valid example for an arrow function?

  • (a,b) => c
  • a, b => {return c;}
  • a, b => c
  • { a, b } => c

Q29. Which concept is defined as a template that can be used to generate different objects that share some shape and/or behavior?

  • class
  • generator function
  • map
  • proxy

Q30. How do you add a comment to JavaScript code?

  • ! This is a comment
  • # This is a comment
  • \\ This is a comment
  • // This is a comment

Q31. If you attempt to call a value as a function but the value is not a function, what kind of error would you get?

  • TypeError
  • SystemError
  • SyntaxError
  • LogicError

Q32. Why would you choose an asynchronous structure for your code?

  • To use ES6 syntax
  • To start tasks that might take some time without blocking subsequent tasks from executing immediately
  • To ensure that parsers enforce all JavaScript syntax rules when processing your code
  • To ensure that tasks further down in your code aren't initiated until earlier tasks have completed

Q33. What is the HTTP verb to request the contents of an existing resource?

  • DELETE
  • GET
  • PATCH
  • POST

Q34. Which tag pair is used in HTML to embed JavaScript?

  • <script></script>
  • <js></js>
  • <javascript></javascript>
  • <code></code>

Q35. Which statement can take a single expression as input and then look through a number of choices until one that matches that value is found?

  • else
  • when
  • if
  • switch

Q36. Which method call is chained to handle a successful response returned by fetch()?

  • done()
  • then()
  • finally()
  • catch()

Q37. Which method do you use to attach one DOM mode to another?

  • attachNode()
  • appendChild()
  • querySelector()
  • getNode()

Q38. Which of the following are not server-side Javascript objects?

  • Date
  • FileUpload
  • Function
  • All of the above

Q39. Which collection object allows a unique value to be inserted only once?

  • Map
  • Array
  • Set
  • Object

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