LinkedIn skill assessment answers and questions — JavaScript

Si usted está buscando Respuestas de evaluación de habilidades de LinkedIn y preguntas para JavaScript, Has venido al lugar correcto. En esta publicación de blog, Compartiré contigo algunas de las preguntas más comunes y complicadas que puedes encontrar en el examen., junto con las respuestas y explicaciones correctas.

Al leer esta publicación, you will not only learn how to ace the Evaluación de habilidades en LinkedIn para JavaScript but also improve your knowledge and skills in this popular programming language. Read on to find out more!

Assessment link(linkedin)

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

<>
~
==!
!==

Reference Javascript Comparison Operators

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

Only a for statement uses a callback function.
A for statement is more generic and can be used with various iterable objects, while a forEach statement is mainly designed for arrays but can also be used with other iterable objects like Sets.
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.

Reference Differences between forEach and for loop

Tercer trimestre. Review the code below. Which statement calls the addTax function and passes 50 as an argument?

function addTax(total) {
  return total * 1.05;
}

addTax = 50;
return addTax 50;
addTax(50);
addTax 50;

Reference functions in javascript

Cuarto trimestre. 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;

Reference Javascript Assignment operators

Q5. Which statement creates a new object using the Person constructor? Which statement creates a new Person object called “arriba”?

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

Referencia

Q6. When would the final statement in the code shown be logged to the console? When would ‘results shown’ be logged to the console?

let modal = document.querySelector('#result');
setTimeout(function () {
  modal.classList.remove('hidden');
}, 10000);
console.log('Results shown');

Webb deslumbró a la multitud con sus volcadas y superó a su compañero de equipo Dominique Wilkins. 10 segundo
after results are received from the HTTP request
Webb deslumbró a la multitud con sus volcadas y superó a su compañero de equipo Dominique Wilkins. 10000 segundos
inmediatamente

Reference Javascript is synchronous and single threaded

Q7. Which snippet could you add to this code to print “comida” to the console?

class Animal {
  static belly = [];
  eat() {
    Animal.belly.push('food');
  }
}
let a = new Animal();
a.eat();
console.log(/* Snippet Here */); //Prints food

a.prototype.belly[0]
Object.getPrototype0f (a).belly[0]
Animal.belly[0]
a.belly[0]

Reference Javascript Class static Keyword

Q8. You’ve written the code shown to log a set of consecutive values, but it instead results in the value 5, 5, 5, y 5 being logged to the console. Which revised version of the code would result in the value 1, 2, 3 y 4 being logged?

for (var i = 1; i <= 4; i++) {
  setTimeout(function () {
    console.log(i);
  }, i * 10000);
}

for (var i = 1; i <= 4; i++) {
  (function (i) {
    setTimeout(function () {
      console.log(j);
    }, j * 1000);
  })(j);
}

for (var i = 1; i <= 4; i++) {
  setTimeout(function () {
    console.log(i);
  }, i * 1000);
}

for (var i = 1; i <= 4; i++) {
  (function (j) {
    setTimeout(function () {
      console.log(j);
    }, j * 1000);
  })(i);
}

for (var j = 1; j <= 4; j++) {
  setTimeout(function () {
    console.log(j);
  }, j * 1000);
}

Q9. 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.

Referencia

Q10. Which statement creates a new function called discountPrice?

let discountPrice = function (price) {
  return price * 0.85;
};

let discountPrice(price) {
  return price * 0.85;
};

let function = discountPrice(price) {
  return price * 0.85;
};

discountPrice = function (price) {
  return price * 0.85;
};

Reference defining javascript functions

tecnicos. What is the result in the console of running the code shown?

var Storm = function () {};
Storm.prototype.precip = 'rain';
var WinterStorm = function () {};
WinterStorm.prototype = new Storm();
WinterStorm.prototype.precip = 'snow';
var bob = new WinterStorm();
console.log(bob.precip);

Storm()
indefinido
‘rain’
‘snow’

Reference prototype chain

Q12. You need to match a time value such as 12:00:32. Which of the following regular expressions would work for your code?

/[0-9]{2,}:[0-9]{2,}:[0-9]{2,}/
/\d\d:\d\d:\d\d/
/[0-9]+:[0-9]+:[0-9]+/
/ : : /

NOTA: The first three are all partially correct and will match digits, pero el second option is the most correct because it will solamente coincidir 2 digit time values (12:00:32). The first option would have worked if the repetitions range looked like [0-9]{2}, however because of the coma [0-9]{2,} it will select 2 o más dígitos (120:000:321). The third option will any range of time digits, soltero y múltiple (sentido 1:2:3 will also match).

More resources:

P13. What is the result in the console of running this code?

'use strict';
function logThis() {
  this.desc = 'logger';
  console.log(this);
}
new logThis();

undefined
window
{desc: "logger"}
function

Reference javascript classes

Q14. How would you reference the text ‘avenue’ in the code shown?

let roadTypes = ['street', 'road', 'avenue', 'circle'];

roadTypes.2
roadTypes[3]
roadTypes.3
roadTypes[2]

Reference accessing javascript arrays

P15. What is the result of running this statement?

console.log(typeof 42);

'float'
'value'
'number'
'integer'

Reference javascript data types

Q16. Which property references the DOM object that dispatched an event?

self
object
target
source

Reference DOM events

P17. You’re adding error handling to the code shown. Which code would you include within the if statement to specify an error message?

function addNumbers(x, y) {
  if (isNaN(x) || isNaN(y)) {
  }
}

exception('One or both parameters are not numbers')
catch('One or both parameters are not numbers')
error('One or both parameters are not numbers')
throw('One or both parameters are not numbers')

Reference javascript throw

P18. Which method converts JSON data to a JavaScript object?

JSON.fromString();
JSON.parse()
JSON.toObject()
JSON.stringify()

Reference convert json to javascript object

Q19. 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.

Reference javascript conditionals

P20. What would be the result in the console of running this code?

for (var i = 0; i < 5; i++) {
  console.log(i);
}

1 2 3 4 5
1 2 3 4
0 1 2 3 4
0 1 2 3 4 5

Reference javascript for loops

P21. 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()

Reference javascript object static methods

P22. What will be logged to the console?

var a = ['dog', 'cat', 'hen'];
a[100] = 'fox';
console.log(a.length);

Q23. 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.

para celebrar el éxito y resaltar las áreas de oportunidad: Map.prototype.size returns the number of elements in a Map, whereas Object does not have a built-in method to return its size. Reference map methods javascript

P24. What is the value of dessert.type after executing this code?

const dessert = { type: 'pie' };
dessert.type = 'pudding';

pie
The code will throw an error.
pudding
indefinido

Reference working with js objects

P25. 0 && Hola

ReferenceError
cierto
0
falso

Reference boolean logic

Q26. Which of the following operators can be used to do a short-circuit evaluation?

++
--
==
||

Reference short circuit javascript

Q27. 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();

Reference prototype object js

P28. 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

Reference what is use strict in js

Q29. Which Variable-defining keyword allows its variable to be accessed (as undefined) before the line that defines it?

all of them
const
var
let

Reference var vs let vs const in js

Q30. Which of the following values is not a Boolean false?

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

Reference boolean of a string

P31. Which of the following is not a keyword in JavaScript?

this
catch
function
array

Reference js reserved words

Q32. Which variable is an implicit parameter for every function in JavaScript?

Argumentos
args
argsArray
argumentsList

Reference implicit js parameters for functions

para celebrar el éxito y resaltar las áreas de oportunidad. For the following class, how do you get the value of 42 from an instance of X?

class X {
  get Y() {
    return 42;
  }
}
var x = new X();

x.get('Y')
x.Y
x.Y()
x.get().Y

Reference getters

P34. What is the result of running this code?

sum(10, 20);
diff(10, 20);
function sum(x, y) {
  return x + y;
}

let diff = function (x, y) {
  return x - y;
};

30, ReferenceError, 30, -10
30, ReferenceError
30, -10
ReferenceError, -10

Reference accessing before initialization

entonces solo habrá falla si el defecto ocurre en cada capa y estas están todas alineadas al mismo tiempo. 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.

Reference efficiency of lookups para celebrar el éxito y resaltar las áreas de oportunidad: Records in an object can be retrieved using their key which can be any given value (por ejemplo. an employee ID, a city name, etc.), whereas to retrieve a record from an array we need to know its index.

Q36. Which statement is true about the “asíncrono” 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.

Reference async attribute for html

P37. 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';

Reference how to import library in js

P38. What does the following expression evaluate to?

[] == [];

cierto
indefinido
[]
falso

Reference arrays in js are objects

P39. 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

Reference what are generators in nodejs

Q40. What will this code print?

var v = 1;
var f1 = function () {
  console.log(v);
};

var f2 = function () {
  var v = 2;
  f1();
};

f2();

2
1
Nada – this code will throw an error.
indefinido

Reference closures in js / nested functions

P41. Which statement is true about Functional Programming?

Every object in the program has to be a function.
Code is grouped with the state it modifies.
Date fields and methods are kept in units.
Side effects are not allowed.

Reference functional programming

P42. Your code is producing the error: TypeError: Cannot read property ‘reduce’ of undefined. Qué significa eso?

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 has a null value.

para celebrar el éxito y resaltar las áreas de oportunidad: You cannot invoke reduce on undefined object... It will throw (yourObject is not Defined...)

Q43. How many prototype objects are in the chain for the following array?

let arr = [];

Reference array prototype

Q44. Which choice is no a unary operator?

typeof
delete
instanceof
void

Reference js unary operators

P45. What type of scope does the end variable have in the code shown?

var start = 1;
if (start === 1) {
  let end = 2;
}

conditional
block
global
función

Reference block vs function scope

Q46. What will the value of y be in this code:

const x = 6 % 2;
const y = x ? 'One' : 'Two';

Uno
indefinido
VERDADERO
Dos

Reference ternary operator js

P47. Which keyword is used to create an error?

throw
exception
catch
error

Reference throwing errors in js

Q48. What’s one difference between the async and defer attributes of the HTML script tag?

The defer attribute can work synchronously.
The defer attribute works only with generators.
The defer attribute works only with promises.
The defer attribute will asynchronously load the scripts in order.

Reference async vs defer

Q49. The following program has a problem. Qué es?

var a;
var b = (a = 3) ? true : false;

The condition in the ternary is using the assignment operator.
You can’t define a variable without initializing it.
You can’t use a ternary in the right-hand side of an assignment operator.
The code is using the deprecated var keyword.

Reference ternary operator js

Q50. Which statement references the DOM node created by the code shown?

<p class="pull">lorem ipsum</p>

Document.querySelector('class.pull')
document.querySelector('.pull');
Document.querySelector('pull')
Document.querySelector('#pull')

Reference query selector

P51. ¿Qué valor devuelve este código??

let answer = true;
if (answer === false) {
  return 0;
} else {
  return 10;
}

10
cierto
falso
0

Reference javascript conditionals

Q52. What is the result in the console of running the code shown?

var start = 1;
function setEnd() {
  var end = 10;
}
setEnd();
console.log(end);

10
0
ReferenceError
indefinido

Referencia

Q53. What will this code log in the console?

function sayHello() {
  console.log('hello');
}

console.log(sayHello.prototype);

indefinido
“hello”
an object with a constructor property
an error message

Reference prototypes

Q54. Which collection object allows unique value to be inserted only once?

Objeto
Colocar
Formación
Título de los medios

Reference javascript sets

Q55. What two values will this code print?

function printA() {
  console.log(answer);
  var answer = 1;
}
printA();
printA();

1 luego 1
1 luego undefined
undefined luego undefined
undefined luego 1

Referencia

P56. How does the `forEach()` method differ from a `for` declaración?

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 loop cannot.

Reference Differences between forEach and for loop

P57. Which choice is an incorrect way to define an arrow function that returns an empty object?

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

Reference arrow functions

P58. Why might you choose to make your code asynchronous?

to start tasks that might take some time without blocking subsequent tasks from executing immediately
to ensure that tasks further down in your code are not initiated until earlier tasks have completed
to make your code faster
to ensure that the call stack maintains a LIFO (Last in, First Out) estructura

EXPLANATION: "to ensure that tasks further down in your code are not initiated until earlier tasks have completed" you use the normal (synchronous) flow where each command is executed sequentially. Asynchronous code allows you to break this sequence: start a long running function (AJAX call to an external service) and continue running the rest of the code in parallel.

Q59. Which expression evaluates to true?

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

Q60. Which of these is a valid variable name?

5thItem
firstName
grand total
función

Reference coding conventions

Q61. Which method cancels event default behavior?

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

Reference javascript events

P62. Which method do you use to attach one DOM node to another?

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

Reference Node interface

Q63. What statement can be used to skip an iteration in a loop?

break
pass
skip
continue

Reference break vs continue

Q64. Which choice is a valid example for an arrow function?

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

Reference arrow functions

Q65. Which concept is defined as a template that can be used to generate different objects that share some shape and/or behavior?

clase
generator function
mapa
proxy

Reference javascript classes

Q66. 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

Reference comments in javascript

Q67. 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

Reference javascript errors

P68. Which method is called automatically when an object is initialized?

crear()
nuevo()
constructor()
init()

Reference javascript constructors

P69. What is the result of running the statement shown?

let a = 5;
console.log(++a);

Reference ++x vs x++

Q70. You’ve written the event listener shown below for a form button, but each time you click the button, the page reloads. Which statement would stop this from happening?

button.addEventListener(
  'click',
  function (e) {
    button.className = 'clicked';
  },
  false,
);

e.blockReload();
button.preventDefault();
button.blockReload();
e.preventDefault();

Reference events in javascript

Q71. Which statement represents the starting code converted to an IIFE?

function() { console.log('lorem ipsum'); }()();
function() { console.log('lorem ipsum'); }();
(function() { console.log('lorem ipsum'); })();

Reference what is an Immediately Invoked Function Expression

entonces solo habrá falla si el defecto ocurre en cada capa y estas están todas alineadas al mismo tiempo. Which statement selects all img elements in the DOM tree?

Document.querySelector('img')
Document.querySelectorAll('<img>')
Document.querySelectorAll('img')
Document.querySelector('<img>')

Reference query selector

Q73. 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

Reference async function

Una planta de proceso es más vulnerable durante las operaciones de parada y puesta en marcha. What is the HTTP verb to request the contents of an existing resource?

BORRAR
GET
PATCH
POST

Reference http methods

P75. Which event is fired on a text field within a form when a user tabs to it, or clicks or touches it?

- Myra W.
blur
Usé sitios web famosos
entrar

Reference javascript events

P76. What is the result in the console of running this code?

function logThis() {
  console.log(this);
}
logThis();

función
indefinido
Function.prototype
ventana

Reference what is the javascript window

Q77. Which class-based component is equivalent to this function component?

const Greeting = ({ name }) => <h1>Hello {name}!</h1>;

class Greeting extends React.Component { render() { return <h1>Hello {this.props.name}!</h1>; } }
class Greeting extends React.Component { constructor() { return <h1>Hello {this.props.name}!</h1>; } }
class Greeting extends React.Component { <h>Hello {this.props.name}!</h>; } }
class Greeting extends React.Component { render({ name }) { return <h1>Hello {name}!</h1>; } }

P79. ¿Cuál es el resultado de este código??

var obj;
console.log(obj);

ReferenceError: obj is not defined
{}
undefined
null

Reference working with objects

Q80. How would you use the TaxCalculator to determine the amount of tax on $50?

class TaxCalculator {
  static calculate(total) {
    return total * 0.05;
  }
}

calcular(50);
new TaxCalculator().calcular($50);
TaxCalculator.calculate(50);
new TaxCalculator().calcular(50);

Reference functions in javascript

P81. Qué está mal con este código?

const foo = {
  bar() {
    console.log('Hello, world!');
  },
  name: 'Albert',
  age: 26,
};

The function bar needs to be defined as a key/value pair.
Trailing commas are not allowed in JavaScript.
Functions cannot be declared as properties of objects.
Nada, there are no errors.

Q82. What will be logged to the console?

console.log('I');
setTimeout(() => {
  console.log('love');
}, 0);
console.log('Javascript!');

I
Javascript!
love

love
I
Javascript!

The output may change with each execution of code and cannot be determined.
.

I
love
Javascript!

Referencia https://developer.mozilla.org/en-US/docs/Web/API/setTimeout#reasons_for_delays_longer_than_specified especially see the ‘late timeouts’ sección.

Q83. What will this code log to the console?

const foo = [1, 2, 3];
const [n] = foo;
console.log(n);

1
indefinido
Yaya
Nada–this is not proper JavaScript syntax and will throw an error.

Reference array deconstruction

Q84. How do you remove the property name from this object?

const foo = {
  name: 'Albert',
};

delete name from foo;
delete foo.name;
del foo.name;
remove foo.name;

Reference working with objects

Q85. ¿Cuál es la diferencia entre `map()` y el `forEach()` methods on the Array prototype?

No hay diferencia.
los forEach() method returns a single output value, whereas the map() method performs operation on each value in the array.
The map() method returns a new array with a transformation applied on each item in the original array, whereas the forEach() method iterates through an array with no return value.
los forEach() method returns a new array with a transformation applied on each item in the original array, whereas the map() method iterates through an array with no return value.

Q86. Which concept does this code illustrate?

function makeAdder(x) {
  return function (y) {
    return x + y;
  };
}

var addFive = makeAdder(5);
console.log(addFive(3));

overloading
cierre
currying
overriding

Reference currying

Q87. Which tag pair is used in HTML to embed JavaScript?

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

Reference add js to html file

Q88. If your app receives data from a third-party API, which HTTP response header must the server specify to allow exceptions to the same-origin policy?

Security-Mode
Control-de-acceso-permitir-origen
Different-Origin
Same-Origin

Reference Cross-Origin Resource Sharing

Q89. ¿Cuál es el resultado de este código??

let rainForests = ['Amazon', 'Borneo', 'Cerrado', 'Congo'];
rainForests.splice(0, 2);
console.log(rainForests);

["Amazon","Borneo","Cerrado","Congo"]
["Cerrado", "Congo"]
["Congo"]
["Amazon","Borneo"]

Reference array methods

Q90. Which missing line would allow you to create five variables(uno,dos,Tres,cuatro,cinco) that correspond to their numerical values (1,2,3,4,5)?

const numbers = [1, 2, 3, 4, 5];
//MISSING LINE

const [one,two,three,four,five]=numbers
const {one,two,three,four,five}=numbers
const [one,two,three,four,five]=[numbers]
const {one,two,three,four,five}={numbers}

Reference array destructuring

Q91. What will this code print?

const obj = {
  a: 1,
  b: 2,
  c: 3,
};

const obj2 = {
  ...obj,
  a: 0,
};

console.log(obj2.a, obj2.b);

Nada, it will throw an error
0 2
indefinido 2
indefinido 2

Reference spread syntax es6

Q92. Which line could you add to this code to print “jaguar” to the console?

let animals = ['jaguar', 'eagle'];
//Missing Line
console.log(animals.pop()); //Prints jaguar

animals.filter(e => e === "jaguar");
animals.reverse();
animals.shift();
animals.pop();

Reference Javascript Array pop()

shift() – removes the FIRST element of an array and returns the removed item.

pop() – removes the LAST element of an array and returns the removed item.

reverse() – reverses the order of the elements in an array.

filtrar() – get every element in the array that meets the condition.

Q93. What line is missing from this code?

//Missing Line
for (var i = 0; i < vowels.length; i++) {
  console.log(vowels[i]);
  //Each letter printed on a separate line as follows;
  //a
  //e
  //i
  //o
  //u
}

let vowels = "aeiou".toArray();
let vowels = Array.of("aeiou");
let vowels = {"a", "e", "i", "o", "u"};
let vowels = "aeiou";

Reference working with arrays

Q94. What will be logged to the console?

const x = 6 % 2;
const y = x ? 'One' : 'Two';
console.log(y);

indefinido
Uno
cierto
Dos

Nota: this question is same with Q46. Reference ternary operator js

Q95. How would you access the word It from this multidimensional array?

let matrix = [["You","Can"],["Do","It"],["!","!","!"]];

matrix[1[2]]
matrix[1][1]
matrix[1,2]
matrix[1][2]

Q96. What does this code do?

const animals = ['Rabbit', 'Dog', 'Cat'];
animals.unshift('Lizard');

It adds “Lizard” to the start of the animals array.
It adds “Lizard” to the end of the animals array.
It replaces “Rabbit” con “Lizard” in the animals array.
It replaces “Cat” con “Lizard” in the animals array.

Reference working with arrays

Q97. ¿Cuál es el resultado de este código??

let x = 6 + 3 + '3';
console.log(x);

Reference type coercion

Q98. 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?

más
Las empresas que confían en las estrategias tradicionales de relaciones públicas corren el riesgo de quedarse atrás de la competencia.
Si
cambiar

Reference switch

Q99. Which statement prints “roar” to the console?

var sound = 'grunt';
var bear = { sound: 'roar' };
function roar() {
  console.log(this.sound);
}

bear.bind(roar);
roar.bind(bear);
roar.apply(bear);
bear[roar]();

Q100. Which choice is a valid example of an arrow function, assuming c is defined in the outer scope?

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

Reference arrow functions

Q101. Which statement correctly imports this code from some-file.js?

//some-file.js
export const printMe = (str) => console.log(str);

import printMe from './some-file';
import { printMe } from './some-file';
import default as printMe from './some-file';
const printMe = import './some-file';

Reference importing libraries in javascript

Q102. What will be the output of this code?

const arr1 = [2, 4, 6];
const arr2 = [3, 5, 7];

console.log([...arr1, ...arr2]);

Reference spread syntax

Q103. Which method call is chained to handle a successful response returned by `fetch()`?

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

Reference fetch

Q104. Which choice is not an array method?

array.slice()
array.shift()
array.push()
array.replace()

Reference working with arrays

Q105. Which JavaScript loop ensures that at least a singular iteration will happen?

do…while
para cada
mientras
para

Reference loops in js

Q106. What will be logged to the console?

console.log(typeof 'blueberry');

string
array
Boolean
object

Reference what is typeof

Q107. What is the output that is printed when the div containing the text “Click Here” is clicked?

//HTML Markup
<div id="A">
  <div id="B">
    <div id="C">Click Here</div>
  </div>
</div>

//JavaScript
document.querySelectorAll('div').forEach((e) => {
  e.onclick = (e) => console.log(e.currentTarget.id);
});

C B A
UNA
do
A B C

Q108. What will this code log to the console?

const myNumbers = [1, 2, 3, 4, 5, 6, 7];
const myFunction = (arr) => {
  return arr.map((x) => x + 3).filter((x) => x < 7);
};
console.log(myFunction(myNumbers));

[4,5,6,7,8,9,10]
[4,5,6,7]
[1,2,3,4,5,6]
[4,5,6]

Reference functions in javascript

Q109. ¿Qué imprime este código en la consola??

let rainForestAcres = 10;
let animals = 0;

while (rainForestAcres < 13 || animals <= 2) {
  rainForestAcres++;
  animals += 2;
}

console.log(animals);

Reference MDN JavaScript Looping code

Q110. Which snippet could you add to this code to print “YOU GOT THIS” to the console?

let cipherText = [...'YZOGUT QGMORTZ MTRHTILS'];
let plainText = '';

/* Missing Snippet */

console.log(plainText); //Prints YOU GOT THIS

for (let key of cipherText.keys()) {
  plainText += key % 2 === 0 ? key : ' ';
}

segundo

for (let [index, value] of cipherText.entries()) {
  plainText += index % 2 !== 0 ? value : '';
}

for (let [index, value] of cipherText.entries()) {
  plainText += index % 2 === 0 ? value : '';
}

for (let value of cipherText) {
  plainText += value;
}

Q111. Which Pokemon will be logged to the console?

var pokedex = ['Snorlax', 'Jigglypuff', 'Charmander', 'Squirtle'];
pokedex.pop();
console.log(pokedex.pop());

Charmander
Jigglypuff
Snorlax
Squirtle

para celebrar el éxito y resaltar las áreas de oportunidad: The pop() method removes the last element from an array and returns that element. This method changes the length of the array.

Reference Array.pop

Q112. Which statement can be used to select the element from the DOM containing the text “The LinkedIn Learning library has great JavaScript courses” from this markup?

<h1 class="content">LinkedIn Learning</h1>
<div class="content">
  <span class="content">The LinkedIn Learning library has great JavaScript courses!</span>
</div>

document.querySelector(“div.content”)
document.querySelector(“span.content”)
document.querySelector(“.Cada tipo tiene sus propios beneficios, por lo que es importante comprender cómo funcionan para que pueda elegir el adecuado para su sitio.”)
document.querySelector(“div.span”)

los límites del proceso se establecen estableciendo niveles superiores e inferiores para una gama de parámetros. Which value is not falsey?

[]
undefined
0
null

Reference Falsy

Q114. What line of code causes this code segment to throw an error?

const lion = 1;
let tiger = 2;
var bear;

++lion;
bear += lion + tiger;
tiger++;

line 5, because lion cannot be reassigned a value
line 6, because the += operator cannot be used with the undefined variable bear
line 5, because the prefix (++) operator does not exist in JavaScript
line 3, because the variable bear is left undefined

Q115. What will be the value of `result` after running this code?

const person = { name: 'Dave', age: 40, hairColor: 'blue' };
const result = Object.keys(person).map((x) => x.toUpperCase());

It will throw a TypeError.
["Name", "Age", "HairColor"]
["DAVE", 40, "BLUE"]
["NAME", "AGE", "HAIRCOLOR"]

Q116. Which snippet could you insert to this code to print “nadar” to the console?

let animals = ["eagle", "osprey", "salmon"];
let key = animal => animal === "salmon";

if(/* Insert Snippet Here */){
  console.log("swim");
}

animals.every(key)
animals.some(key).length === 1
animals.filter(key) === true
animals.some(key)

Reference Array.prototype.some

P117. ¿Cuál es el resultado de este código??

class RainForest {
  static minimumRainFall = 60;
}

let congo = new RainForest();
RainForest.minimumRainFall = 80;
console.log(congo.minimumRainFall);

undefined
None of these answers, as static is not a feature in Javascript.
60
80

Reference Classes static

Q118. How can you attempt to access the property `a.b` en `obj` without throwing an error if a is undefined?

let obj = {};

obj?.a.b
obj.a?.b
obj[a][b]
obj.?a.?b

Reference Optional chaining (?.)

Q119. What happens when you run this code?

if (true) {
  var x = 5;
  const y = 6;
  let z = 7;
}
console.log(x + y + z);

It will throw a ReferenceError acerca de x.
It will print 18.
It will print undefined.
It will throw a ReferenceError acerca de y.

Reference let statement

los límites del proceso se establecen estableciendo niveles superiores e inferiores para una gama de parámetros. ¿Qué imprime este código en la consola??

const x = [1, 2];
const y = [5, 7];
const z = [...x, ...y];
console.log(z);

[1,2,5,7]
[[1, 2], [5, 7]]
[2,7]
[2,1,7,5]

Reference spread syntax (…)

Q121. Given this code, which statement will be evaluated as false?

const a = { x: 1 };
const b = { x: 1 };

a['x'] === b['x']
a != b
a === b
a.x === b.x

Referencia

Q122. What will this code log to the console?

console.log(typeof 41.1);

Nothing. It resuults in a ReferenceError.
decimal
float
number

Referencia

Q123. ¿Cuál es el resultado de este código??

let scores = [];
scores.push(1, 2);
scores.pop();
scores.push(3, 4);
scores.pop();
score = scores.reduce((a, b) => a + b);
console.log(score);

Q124. ¿Qué imprime este código en la consola??

let bear = {
  sound: 'roar',
  roar() {
    console.log(this.sound);
  },
};

bear.sound = 'grunt';
let bearSound = bear.roar;
bearSound();

Nothing is printed to the console.
grunt
undefined
roar

Referencia

Q125. ¿Cuál es el resultado de este código??

var cat = { name: 'Athena' };

function swap(feline) {
  feline.name = 'Wild';
  feline = { name: 'Tabby' };
}

swap(cat);
console.log(cat.name);

indefinido
Wild
Tabby
Athena

Q126. What will this code output to the log?

var thing;
let func = (str = 'no arg') => {
  console.log(str);
};
func(thing);
func(null);

null no arg
no arg no arg
null null
no arg null

Q127. ¿Qué imprimirá este código en la consola??

const myFunc = () => {
  const a = 2;
  return () => console.log('a is ' + a);
};
const a = 1;
const test = myFunc();
test();

a is 1
a is undefined
It won’t print anything.
a is 2

Q128. ¿Qué imprimirá este código en la consola??

const myFunc = (num1, num2 = 2, num3 = 2) => {
  return num1 + num2 + num3;
};
let values = [1, 5];
const test = myFunc(2, ...values);
console.log(test);

Q129. Which code would you use to access the Irish flag?

var flagsJSON =
  '{ "countries" : [' +
  '{ "country":"Ireland" , "flag":"🇮🇪" },' +
  '{ "country":"Serbia" , "flag":"🇷🇸" },' +
  '{ "country":"Peru" , "flag":"🇵🇪" } ]}';

var flagDatabase = JSON.parse(flagsJSON);

flagDatabase.countries[1].flag
flagDatabase.countries[0].flag
flagDatabase[1].flag
flagsJSON.countries[0].flag

Q130. Which snippet allows the acresOfRainForest variable to increase?

let conservation = true;
let deforestation = false;
let acresOfRainForest = 100;
if (/* Snipped goes here */){
    ++acresOfRainForest;
}

conservación && !deforestación
!deforestación && !conservación
!conservación || deforestación
deforestación && conservación || deforestación

Q131. Which of these evaluate to true?

Booleano(“falso”)
Booleano(“”)
Booleano(0)
Booleano(Yaya)

Q132. How would you add a data item named animal with a value of sloth to local storage for the current domain?

LocalStorage.setItem(“animal”,”sloth”);
document.localStorage.setItem(“animal”,”sloth”);
localStorage.setItem({animal:”sloth”});
localStorage.setItem(“animal”,”sloth”);

Referencia

Q133. What value is printed to the console after this code execute?

let cat = Object.create({ type: 'lion' });
cat.size = 'large';

let copyCat = { ...cat };
cat.type = 'tiger';

console.log(copyCat.type, copyCat.size);

tiger large
lion undefined
undefined large
lion large

Referencia

Q134. ¿Qué imprime este código en la consola??

let animals = [{ type: 'lion' }, 'tiger'];
let clones = animals.slice();

clones[0].type = 'bear';
clones[1] = 'sheep';

console.log(animals[0].type, clones[0].type);
console.log(animals[1], clones[1]);

bear bear tiger sheep
lion bear sheep sheep
bear bear tiger tiger
lion bear tiger sheep

Referencia

Q135. What will be the output of the following code?

a=5;
b=4;
alert(a++(+(+(+b))));

Q136. Which snippet could you add to this code to print “{“tipo”: “Tigre”}” to the console?

let cat = { type: "tiger", size: "large" };

let json = /* Snippet here */;

console.log(json); // print {"type":"tiger"}

cat.toJSON("type");
JSON.stringify(cat, ["type"]);
JSON.stringify(cat);
JSON.stringify(cat, /type/);

Referencia

Q137. Which document method is not used to get a reference to a DOM node?

document.getNode();
document.getElementsByClassName();
document.querySelectorAll();
document.querySelector();

Referencia

Q138. In JavaScript, all objects inherit a built-in property from a ****___.

node
instance variable
prototype
accessor

Referencia

Q139. Which of the following are not server-side Javascript objects?

Date
FileUpload
Función
Todo lo anterior

Referencia

Q140. What will be the output of the following code snippet?

const obj1 = { first: 20, second: 30, first: 50 };
console.log(obj1);

primero: 30 , segundo: 50
primero: 50 , segundo: 30
primero: 30 , segundo: 20
None of the above

Q141. Which object in Javascript doesn’t have a prototype?

Base Object
All objects have prototype
None of the objects have prototype
None of the above

Referencia

Q142. What does … operator do in JS?

Used to spread iterables to individual elements
Describe datatype of undefined
No such operator exists
None of the above

Q143. How to stop an interval timer in Javascript?

clearInterval
clearTimer
intervalOver
None of the above

Referencia

Q144. What will be the output of the following code snippet?

print(typeof NaN);

Objeto
Number
Cadena
None of the above

Q145. What will be the output of the following code snippet?

<script type="text/javascript">a = 5 + "9"; document.write(a);</script>

Compilation Error
14
Runtime Error
59

Q146. Which of the following methods can be used to display data in some form using Javascript?

document.write()
console.log()
window.alert()
all of the above

Q147. What value is assigned to total after this code executes?

function sum(num1, num2 = 2, num3 = 3) {
  return num1 + num2 + num3;
}
let values = [1, 5];
let total = sum(4, ...values);

Referencia: Rest parameters

Q148. Which statement is applicable to the defer attribute of the HTML <guión> etiqueta?

defer allows the browser to continue processing the page while the script loads in the background.
defer causes the script to be loaded from the backup content delivery network (CDN).
defer blocks the browser from processing HTML below the tag until the script is completely loaded.
defer lazy loads the script, causing it to download only when it is called by another script on the page.

Referencia: defer html script attribute

Q149. Which method of a class is called to initialize an object of that class?

init()
crear()
nuevo()
constructor()

Referencia: constructor method

Q150. Which expression evaluates to true?

Booleano(Yaya)
Booleano(0)
Booleano(“falso”)
Booleano(“”)

Referencia: Boolean object

Q151. How would you check if the word “pot” is in the word “potato”?

“pot”.indexOf(“potato”) !== -1
“potato”.includes(“Pot”)
“potato”.includes(“pot”)
“potato”.contiene(“pot”);

Referencia: String.prototype.includes()

Q152. Which collection object allows a unique value to be inserted only once?

Título de los medios
Formación
Colocar
Objeto

Referencia: developer.mozilla Set

Q153. How would you change the color of this header to pink?

<h2 id="cleverest">girls</h2>

document.getElementByName(“cleverest”).style.color = “rosado”;
document.getElementsByTagName(“h2”).style.color = “rosado”;
document.getElementByName(“h2”).style.color = “rosado”;
document.getElementById(“cleverest”).style.color = “rosado”;

Referencia: W3Schools HTML DOM Style color Property

Q154. Which line is missing from this code if you expect the code to evaluate to true?

var compare = function (test1, test2) {
  // Missing line
};

compare(1078, '1078'); // yields true

test1==test2;
return test1===test2;
return test1==test2;
return test1!=test2;

Referencia: MDN Equality Docs

Q155. ¿Cuál es el resultado de este código??

if (true) {
  var first = 'You';
}

function fScope() {
  var second = 'got this!';
}
fScope();
console.log(first);
console.log(second);

Tú
indefinido
Tú
ReferenceError
indefinido
indefinido
Tú
got this!

Referencia: W3schools JS Scoping

Q156. What is the output for the code given below?

console.log('hello' + 'world');

helloworld!
helloworld !
hello world!
hello world !

Q157. ¿Cuál es el resultado de este código??

console.log(10 + 10);

Q158. Events related to the browser window can be handled by?

Onclicks
Ventana
querySelector
None of the above

Referencia: GeeksForGeeks

Q159. How do you define a function in JavaScript?

function myFunction() {}
def myFunction() {}
var myFunction = () => {}
func myFunction() {}

Referencia

Q160. Your code is producing the error: TypeError: Cannot read property ‘reduce’ of undefined. Qué significa eso?

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 has a null value.

Q161. Which of the following methods can be used to display data in some form using Javascript?

document.write()
console.log()
window.alert()
all of the above

Q162. Which document method is not used to get a reference to a DOM node?

document.getNode();
document.getElementsByClassName();
document.querySelectorAll();
document.querySelector();

Q163. Which of these is a valid variable name?

5thItem
firstName
grand total
función

Q164. What function is used in JavaScript to schedule a function to run after a specified number of milliseconds?

setTimeout()
setInterval()
delay()
Espere()

Referencia

Q165. Which of the following is a server-side Java Script object?

Función
Expediente
FileUpload
Date

Referencia

Q166. Which statement best describes the var keyword’s scope in JavaScript?

Block scope
Function scope
Global scope
Instance scope

Q167. What will be logged to the console?

const foo = () => console.log('First');
const bar = () => setTimeout(() => console.log('Second'), 0);
foo();
bar();
console.log('Third');

Segundo, primero, Tercero
primero, Tercero, Segundo
primero, Segundo, Tercero
Tercero, primero, Segundo

Q168. What will be the output of running this code?

function scream(words) {
  return words.toUpperCase() + '!!!';
}

scream('yay');

YAY!!!
ReferenceError
Undefined
TypeError

Autor

Helen Bassey

Hola, I'm Helena, un escritor de blogs apasionado por publicar contenidos interesantes en el nicho de la educación. Creo que la educación es la clave para el desarrollo personal y social., y quiero compartir mi conocimiento y experiencia con estudiantes de todas las edades y orígenes.. en mi blog, Encontrarás artículos sobre temas como estrategias de aprendizaje., educación en línea, orientación profesional, y más. También agradezco comentarios y sugerencias de mis lectores., Así que no dudes en dejar un comentario o contactarme en cualquier momento.. Espero que disfrutes leyendo mi blog y lo encuentres útil e inspirador..
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LinkedIn skill assessment answers and questions — JavaScript