Examen completo de JavaScript I Examen con Desarrollador JavaScript Válido I Volcos de exámenes en línea

1. Refer to the following code block:





What is the console output?

2. CORRECT TEXT

Given the requirement to refactor the code above to JavaScript class format, which class definition is correct?





A)





B)





C)





D)

3. Which code change should be done for the console to log the following when 'Click me!' is clicked'





> Row log

> Table log

4. Which statement can a developer apply to increment the browser's navigation history without a page refresh?

Which statement can a developer apply to increment the browser's navigation history without a page refresh?

5. A developer is required to write a function that calculates the sum of elements in an array but is getting undefined every time the code is executed.

The developer needs to find what is missing in the code below.

Const sumFunction = arr => {

Return arr.reduce((result, current) => {

//

Result += current;

//

), 10);

);

Which option makes the code work as expected?

6. Refer to code below:

function Person() {

this.firstName = ’John’;

}

Person.prototype ={

Job: x => ‘Developer’

};

const myFather = new Person();

const result =myFather.firstName + ‘ ‘ + myFather.job();

What is the value of the result after line 10 executes?

7. A developer wrote the following code to test a sum3 function that takes in an array of numbers and returns the sum of the first three numbers in the array, and the test passes.

A different developer made changes to the behavior of sum3 to instead sum only the first two numbers present in the array.





Which two results occur when running this test on the updated sum3 function? Choose 2 answers

8. Refer to the code below:

Let textValue = ’1984’;

Which code assignment shows a correct way to convert this string to an integer?

9. In the browser, the window object is often used to assign variables that require the broadest scope in an application Node.js application does not have access to the window object by default.

Which two methods are used to address this? Choose 2 answers

10. Given the following code:





is the output of line 02?

11. Which two code snippets show working examples of a recursive function? Choose 2 answers

12. Refer to the code below:

function changeValue(param) {

Param =5;

}

Let a =10;

Let b =5;

changeValue(b);

Const result = a+ “ - ”+ b;

What is the value of result when code executes?

13. Consider type coercion, what does the following expression evaluate to?

True + 3 + ‘100’ + null

14. A developer uses a parsed JSON string to work with user information as in the block below:

01 const userInformation ={

02 “ id ” : “user-01”,

03 “email” : “[email protected]”,

04 “age” : 25

Which two options access the email attribute in the object? Choose 2 answers

15. A developer is setting up a Node,js server and is creating a script at the root of the source code, index,js, that will start the server when executed. The developer declares a variable that needs the folder location that the code executes from.

Which global variable can be used in the script?

16. Refer to code below:

Function muFunction(reassign){

Let x = 1;

var y = 1;

if( reassign ) {

Let x= 2;

Var y = 2;

console.log(x);

console.log(y);}

console.log(x);

console.log(y);}

What is displayed when myFunction(true) is called?

17. A developer needs to test this function:

01 const sum3 = (arr) => (

02 if (!arr.length) return 0,

03 if (arr.length === 1) return arr[0],

04 if (arr.length === 2) return arr[0] + arr[1],

05 return arr[0] + arr[1] + arr[2],

06 );

Which two assert statements are valid tests for the function? Choose 2 answers

18. Refer to the code below:

let timeFunction =() => {

console.log(‘Timer called.”);

};

let timerId = setTimeout (timedFunction, 1000);

Which statement allows a developer to cancel the scheduled timed function?

19. Refer to the code below

let inArray = [[1,2],[3,4,5]];

which two statements results in the array [1,2,3,4,5]? choose 2 answer

20. Which code statement correctly retrieves and returns an object from localStorage?

21. Refer to the code below:

const addBy =?

const addByEight =addBy(8);

const sum = addBYEight(50);

Which two functions can replace line 01 and return 58 to sum? Choose 2 answers

22. A developer is leading the creation of a new browser application that will serve a single page application. The team wants to use a new web framework Minimalsit.js. The Lead developer wants to advocate for a more seasoned web framework that already has a community around it.

Which two frameworks should the lead developer advocate for? Choose 2 answers

23. Refer to the code below:

function foo () {

const a =2;

function bat() {

console.log(a);

}

return bar;

}

Why does the function bar have access to variable a?

24. Refer to the code below:

const event = new CustomEvent(

//Missing Code

);

obj.dispatchEvent(event);

A developer needs to dispatch a custom event called update to send information about recordId.

Which two options could a developer insert at the placeholder in line 02 to achieve this? Choose 2 answers

25. A team that works on a big project uses npm to deal with projects dependencies.

A developer added a dependency does not get downloaded when they execute npm install.

Which two reasons could be possible explanations for this? Choose 2 answers

26. Which statement accurately describes the behaviour of the async/ await keyworks?

27. bar, awesome is a popular JavaScript module. the versions publish to npm are:





Teams at Universal Containers use this module in a number of projects.

A particular project has the package, json definition below.





A developer runs this command: npm install.

Which version of bar .awesome is installed?

28. myArraym can have one level, two levels, or more levels.

Which statement flattens myArray when it can be arbitrarily nested?

29. A developer creates a class that represents a blog post based on the requirement that a Post should have a body author and view count.

The Code shown Below:

Class Post {

// Insert code here This.body =body This.author = author; this.viewCount = viewCount;

}

}

Which statement should be inserted in the placeholder on line 02 to allow for a variable to be set to a new instanceof a Post with the three attributes correctly populated?

30. A developer writers the code below to calculate the factorial of a given number.

Function factorial(number) {

Return number + factorial(number -1);

}

factorial(3);

What is the result of executing line 04?

31. Given the following code:

document.body.addEventListener(‘ click ’, (event) => {

if (/* CODE REPLACEMENT HERE */) {

console.log(‘button clicked!’);

)

});

Which replacement for the conditional statement on line 02 allows a developer to correctly determine that a button on page is clicked?

32. A developer wants to iterate through an array of objects and count the objects and count

the objects whose property value, name, starts with the letter N.

Const arrObj = [{“name” : “Zach”}, {“name” : “Kate”},{“name” : “Alise”},{“name” :

“Bob”},{“name” :

“Natham”},{“name” : “nathaniel”}

Refer to the code snippet below:

01 arrObj.reduce(( acc, curr) => {

02 //missing line 02

02 //missing line 03

04 ). 0);

Which missing lines 02 and 03 return the correct count?

33. Given the following code:





What will be the first four numbers logged?

34. Refer to the code below:

console.log(‘’start);

Promise.resolve(‘Success’). then(function(value) {

console.log(‘Success’);

});

console.log(‘End’);

What is the output after the code executes successfully?

35. The developer wants to test the array shown:

const arr = Array(5).fill(0)

Which two tests are the most accurate for this array? Choose 2 answers:

36. A developer wants to create an object from a function in the browser using the code below:

Function Monster() { this.name = ‘hello’ };

Const z = Monster();

What happens due to lack of the new keyword on line 02?

37. Refer to the code declarations below:





Which three expressions return the string JavaScript? Choose 3 answers

38. Refer to the following array:

Let arr1 = [ 1, 2, 3, 4, 5 ];





Which two lines of code result in a second array, arr2 being created such that arr2 is not a reference to arr1?

39. A test has a dependency on database. query. During the test, the dependency is replaced with an object called database with the method, Calculator query, that returns an array. The developer does not need to verify how many times the method has been called.

Which two test approaches describe the requirement? Choose 2 answers

40. 1.At Universal Containers, every team has its own way of copying JavaScript objects.

The code snippet shows an Implementation from one team:





What is the output of the code execution?

41. The developer has a function that prints “Hello” to an input name.

To test this, thedeveloper created a function that returns “World”. However the following snippet does not print “ Hello World”.





What can the developer do to change the code to print “Hello World”?

42. Given the following code:

Let x =null;

console.log(typeof x);

What is the output of the line 02?

43. A developer receives a comment from the Tech Lead that the code given below has error:

const monthName = ‘July’;

const year = 2019;

if(year === 2019) {

monthName = ‘June’;

}

Which line edit should be made to make this code run?

44. Given the JavaScript below:





Which code should replace the placeholder comment on line 05 to highlight accounts that match the search string'

45. A developer creates a generic function to log custom messages in the console.

To do this, the function below is implemented.

01 function logStatus(status){

02 console./*Answer goes here*/{‘Item status is: %s’, status};

03 }

Which three console logging methods allow the use of string substitution in line 02?

46. Universal Containers recently launched its new landing page to host a crowd-funding campaign. The page uses an external library to display some third-party ads.

Once the page is fully loaded, it creates more than 50 new HTML items placed randomly inside the DOM, like the one in the code below:





All the elements includes the same ad-library-item class, They are hidden by default, and they are randomly displayed while the user navigates through the page.

47. Given the following code:

Let x =(‘15’ + 10)*2;

What is the value of a?

48. A developer has the following array of hourly wages:

Let arr = (8, 5, 9, 75, 11, 25, 7, 75, 13, 25);

For workers making less than $10 an hour rate should be multiple by 1.25 and returned in a new array.

How should the developer implement the request?

49. Refer to the code below:





After running this code, which result is displayed on the console?

50. CORRECT TEXT

Refer to the string below.

Const str=’Salesforce’;

Which two statements results in the word 'Sales'?

51. Refer to the HTML below:





Which JavaScript statement results in changing “ The Lion.”?

52. A developer writes the code below to calculate the factorial of a given number function sum(number)

{

return number * sum(number-1);

}

sum (3);

what is the result of executing the code?

53. Which three actions can be using the JavaScript browser console? Choose 3 answers:

54. Refer to the code below:





Which value can a developer expect when referencing country,capital,cityString?

55. CORRECT TEXT

Refer the following code





what is the value of array after code executes?

56. Refer to the following code:

Let obj ={

Foo: 1,

Bar: 2

}

Let output =[],

for(let something in obj{

output.push(something);

}

console.log(output);

What is the output line 11?

57. Which option is a core Node,js module?

58. There is a new requirement for a developer to implement a currPrice method that will return the current price of the item or sales.





What is the output when executing the code above?

59. Refer to the following object.





How can a developer access the fullName property for dog?

60. Refer to code below:

Let a =’a’;

Let b;

// b = a; console.log(b);

What is displayed when the code executes?

61. Given the code below:

01 function GameConsole (name) {

02 this.name = name;

3 }

4

5 GameConsole.prototype.load = function(gamename) {

6 console.log( ` $(this.name) is loading a game : $(gamename) …`);

7 )

08 function Console 16 Bit (name) {

09 GameConsole.call(this, name) ;

10 }

11 Console16bit.prototype = Object.create ( GameConsole.prototype) ;

12 //insert code here

13 console.log( ` $(this.name) is loading a cartridge game : $(gamename) …`);

14 }

15 const console16bit = new Console16bit(‘ SNEGeneziz ’);

16 console16bit.load(‘ Super Nonic 3x Force ’);

What should a developer insert at line 15 to output the following message using the method?

> SNEGeneziz is loading a cartridge game: Super Monic 3x Force . . .

62. Refer to the code:





Given the code above, which three properties are set for pet1? Choose 3 answers

63. A Developer wrote the following code to test a sum3 function that takes in an array of numbers and returns the sum of the first three number in the array,

The test passes:

Let res = sum2([1, 2, 3 ]) ;

console.assert(res === 6 );

Res = sum3([ 1, 2, 3, 4]);

console.assert(res=== 6);

A different developer made changes to the behavior of sum3 to instead sum all of the numbers present in the array. The test passes:

Which two results occur when running the test on the updated sum3 function? Choose 2 answers

64. Refer to the code below:

let sayHello = () => {

console.log (‘Hello, world!’);

};

Which code executes sayHello once, two minutes from now?

65. Considering type coercion, what does the following expression evaluate to?

True + ‘13’ + NaN

66. A developer wrote the following code:

01 let X = object.value;

02

03 try {

4 handleObjectValue(X);

5 } catch (error) {

6 handleError(error);

7 }

The developer has a getNextValue function to execute after handleObjectValue(), but does not want to execute getNextValue() if an error occurs.

How can the developer change the code to ensure this behavior?

67. A developer has two ways to write a function:

Option A:

function Monster() {

This.growl = () => {

Console.log (“Grr!”);

}

}

Option B:

function Monster() {};

Monster.prototype.growl =() => {

console.log(“Grr!”);

}

After deciding on an option, the developer creates 1000 monster objects.

How many growl methods are created with Option A Option B?

68. Cloud Kicks has a class to represent items for sale in an online store, as shown below:

Class Item{

constructor (name, price){

this.name = name;

this.price = price;

}

formattedPrice(){

return ‘s’ + String(this.price);}}

A new business requirement comes in that requests a ClothingItem class that should have all of the properties and methods of the Item class but will also have properties that are specific to clothes.

Which line of code properly declares the clothingItem class such that it inherits from Item?

69. is below:

<input type=”file” onchange=”previewFile()”>

<img src=”” height=”200” alt=”Image Preview…”/>

The JavaScript portion is:

01 function previewFile(){

02 const preview = document.querySelector(‘img’);

03 const file = document.querySelector(‘input[type=file]’).files[0];

04 //line 4 code

05 reader.addEventListener(“load”, () => {

06 preview.src = reader.result;

07 },false);

08 //line 8 code

09 }

In lines 04 and 08, which code allows the user to select an image from their local computer, and to display the image in the browser?

70. A developer wants to use a module named universalContainersLib and then call functions from it.

How should a developer import every function from the module and then call the functions foo and bar?