Here, We see JavaScript LinkedIn Skill Assessment Answer. This assessment test consists of 15-20 MCQs to demonstrate your knowledge of your selected skills. MCQs come from different topics – JavaScript Data Types and Structures; Functions, Objects, and Classes, JavaScript Fundamentals, Logic and Control Flow, and Web Development..
List of all LinkedIn Skills Assessment Answer
JavaScript LinkedIn Skill Assessment Answer
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
Q3. Review the code below. Which statement calls the addTax function and passes 50 as an argument?
functionaddTax(total) {
return total * 1.05;
}
Code language: JavaScript (javascript)
- addTax = 50;
- return addTax 50;
- addTax(50);✔
- addTax 50;
Reference functions in javascript
Q4. 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 “student”?
- var student = new Person();✔
- var student = construct Person;
- var student = Person();
- var student = construct Person();
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');
Code language: JavaScript (javascript)
- after 10 second
- after results are received from the HTTP request
- after 10000 seconds
- immediately✔
Reference Javascript is synchronous and single-threaded
Q7. Which snippet could you add to this code to print “food” to the console?
classAnimal {
static belly = [];
eat() {
Animal.belly.push('food');
}
}
let a = newAnimal();
a.eat();
console.log(<em>/* Snippet Here */</em>); <em>//Prints food</em>
Code language: JavaScript (javascript)
- 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, and 5 being logged to the console. Which revised version of the code would result in the value 1, 2, 3 and 4 being logged?
-
A
for (var i = 1; i <= 4; i++) {
setTimeout(function () {
console.log(i);
}, i * 10000);
}
Code language: JavaScript (javascript)
-
B
for (var i = 1; i <= 4; i++) {
(function (i) {
setTimeout(function () {
console.log(j);
}, j * 1000);
})(j);
}
Code language: JavaScript (javascript)
-
C
for (var i = 1; i <= 4; i++) {
setTimeout(function () {
console.log(i);
}, i * 1000);
}
Code language: JavaScript (javascript)
-
D
✔
<strong>for (var i = 1; i <= 4; i++) {
(function (j) {
setTimeout(function () {
console.log(j);
}, j * 1000);
})(i);
}
</strong>
Code language: JavaScript (javascript)
-
E
for (var j = 1; j <= 4; j++) {
setTimeout(function () {
console.log(j);
}, j * 1000);
}
Code language: JavaScript (javascript)
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.
Q10. Which statement creates a new function called discountPrice?
-
A
let discountPrice = function (price) {
return price * 0.85;
};
Code language: JavaScript (javascript)
-
B
letdiscountPrice(price) {
return price * 0.85;
};
Code language: JavaScript (javascript)
-
C
letfunction = discountPrice(price) {
return price * 0.85;
};
Code language: JavaScript (javascript)
-
D
✔
<strong>discountPrice = function (price) {
return price * 0.85;
};
</strong>
Code language: JavaScript (javascript)
Reference defining javascript functions
Q11. What is the result in the console of running the code shown?
varStorm = function () {};
Storm.prototype.precip = 'rain';
varWinterStorm = function () {};
WinterStorm.prototype = newStorm();
WinterStorm.prototype.precip = 'snow';
var bob = newWinterStorm();
console.log(bob.precip);
Code language: JavaScript (javascript)
- Storm()
- undefined
- ‘rain’
- ‘snow’✔
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]+/
- / : : /
NOTE: The first three are all partially correct and will match digits, but the second option is the most correct because it will only match 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 comma [0-9]{2,}
it will select 2 or more digits (120:000:321). The third option will any range of time digits, single and multiple (meaning 1:2:3
will also match).
More resources:
Q13. What is the result in the console of running this code?
'use strict';
functionlogThis() {
this.desc = 'logger';
console.log(this);
}
newlogThis();
Code language: JavaScript (javascript)
- undefined
- window
- {desc: “logger”}✔
- function
Q14. How would you reference the text ‘avenue’ in the code shown?
let roadTypes = ['street', 'road', 'avenue', 'circle'];
Code language: JavaScript (javascript)
- roadTypes.2
- roadTypes[3]
- roadTypes.3
- roadTypes[2]✔
Reference accessing javascript arrays
Q15. What is the result of running this statement?
console.log(typeof42);
Code language: JavaScript (javascript)
- ‘float’
- ‘value’
- ‘number’✔
- ‘integer’
Reference javascript data types
Q16. Which property references the DOM object that dispatched an event?
- self
- object
- target✔
- source
Q17. You’re adding error handling to the code shown. Which code would you include within the if statement to specify an error message?
functionaddNumbers(x, y) {
if (isNaN(x) || isNaN(y)) {
}
}
Code language: JavaScript (javascript)
- 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’)✔
Q18. 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 statements.
Reference javascript conditionals
Q20. What would be the result in the console of running this code?
for (var i = 0; i < 5; i++) {
console.log(i);
}
Code language: JavaScript (javascript)
- 1 2 3 4 5
- 1 2 3 4
- 0 1 2 3 4✔
- 0 1 2 3 4 5
Reference javascript for loops
Q21. 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
Q22. What will be logged to the console?
var a = ['dog', 'cat', 'hen'];
a[100] = 'fox';
console.log(a.length);
Code language: JavaScript (javascript)
- 101✔
- 3
- 4
- 100
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.
Explanation: 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
Q24. What is the value of dessert.type after executing this code?
const dessert = { type: 'pie' };
dessert.type = 'pudding';
Code language: JavaScript (javascript)
- pie
- The code will throw an error.
- pudding✔
- undefined
Reference working with js objects
Q25. 0 && hi
- ReferenceError
- true
- 0✔
- false
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();
Q28. 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”)✔
Q31. Which of the following is not a keyword in JavaScript?
- this
- catch
- function
- array✔
Q32. Which variable is an implicit parameter for every function in JavaScript?
- Arguments✔
- args
- argsArray
- argumentsList
Reference implicit js parameters for functions
Q33. For the following class, how do you get the value of 42 from an instance of X?
classX {
getY() {
return42;
}
}
var x = newX();
Code language: JavaScript (javascript)
- x.get(‘Y’)
- x.Y✔
- x.Y()
- x.get().Y
Q34. What is the result of running this code?
sum(10, 20);
diff(10, 20);
functionsum(x, y) {
return x + y;
}
let diff = function (x, y) {
return x - y;
};
Code language: JavaScript (javascript)
- 30, ReferenceError, 30, -10
- 30, ReferenceError✔
- 30, -10
- ReferenceError, -10
Reference accessing before initialization
Q35. 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 Explanation: Records in an object can be retrieved using their key which can be any given value (e.g. 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 “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.✔
Reference async attribute for html
Q37. 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
Q38. What does the following expression evaluate to?
[] == [];
- true
- undefined
- []
- false✔
Reference arrays in js are objects
Q39. 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();
Code language: JavaScript (javascript)
- 2
- 1✔
- Nothing – this code will throw an error.
- undefined
Reference closures in js / nested functions
Q41. 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
Q42. 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 has a null value.
Explanation: 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?
<code>let arr = [];</code>
Code language: HTML, XML (xml)
- 3
- 2✔
- 0
- 1
Q44. Which choice is not a unary operator?
- typeof
- delete
- instanceof✔
- void
Q45. What type of scope does the end variable have in the code shown?
var start = 1;
if (start === 1) {
let end = 2;
}
Code language: JavaScript (javascript)
- conditional
- block✔
- global
- function
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';
Code language: JavaScript (javascript)
- One
- undefined
- TRUE
- Two✔
Q47. 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.✔
Q49. The following program has a problem. What is it?
var a;
var b = (a = 3) ? true : false;
Code language: JavaScript (javascript)
- 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.
Q50. Which statement references the DOM node created by the code shown?
<p class="pull">lorem ipsum</p>
Code language: HTML, XML (xml)
- Document.querySelector(‘class.pull’)
- document.querySelector(‘.pull’);✔
- Document.querySelector(‘pull’)
- Document.querySelector(‘#pull’)
Q51. What value does this code return?
let answer = true;
if (answer === false) {
return0;
} else {
return10;
}
Code language: JavaScript (javascript)
- 10✔
- true
- false
- 0
Reference javascript conditionals
Q52. What is the result in the console of running the code shown?
var start = 1;
functionsetEnd() {
var end = 10;
}
setEnd();
console.log(end);
Code language: JavaScript (javascript)
- 10
- 0
- ReferenceError✔
- undefined
Q53. What will this code log in the console?
functionsayHello() {
console.log('hello');
}
console.log(sayHello.prototype);
Code language: JavaScript (javascript)
- undefined
- “hello”
- an object with a constructor property✔
- an error message
Q54. Which collection object allows unique value to be inserted only once?
- Object
- Set✔
- Array
- Map
Q55. What two values will this code print?
functionprintA() {
console.log(answer);
var answer = 1;
}
printA();
printA();
Code language: JavaScript (javascript)
-
1
then1
-
1
then undefined - undefined then undefined✔
- undefined then
1
Q56. How does the forEach() 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 loop cannot.
Reference Differences between forEach and for loop
Q57. Which choice is an incorrect way to define an arrow function that returns an empty object?
- => ({})
- => {}✔
- => { return {};}
- => (({}))
Q58. 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 been completed
- to make your code faster
- to ensure that the call stack maintains a LIFO (Last in, First Out) structure
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
- function
Q61. Which method cancels event default behavior?
- cancel()
- stop()
- preventDefault()✔
- prevent()
Q62. Which method do you use to attach one DOM node to another?
- attachNode()
- getNode()
- querySelector()
- appendChild()✔
Q63. What statement can be used to skip an iteration in a loop?
- break
- pass
- skip
- 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
Q65. 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
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
Q68. Which method is called automatically when an object is initialized?
- create()
- new()
- constructor()✔
- init()
Reference javascript constructors
Q69. What is the result of running the statement shown?
let a = 5;
console.log(++a);
Code language: JavaScript (javascript)
- 4
- 10
- 6✔
- 5
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,
);
Code language: JavaScript (javascript)
- 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
Q72. Which statement selects all img elements in the DOM tree?
- Document.querySelector(‘img’)
- Document.querySelectorAll(‘<img>’)
- Document.querySelectorAll(‘img’)✔
- Document.querySelector(‘<img>’)
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
Q74. What is the HTTP verb to request the contents of an existing resource?
- DELETE
- GET✔
- PATCH
- POST
Q75. Which event is fired on a text field within a form when a user tabs to it, or clicks or touches it?
- focus✔
- blur
- hover
- enter
Q76. What is the result in the console of running this code?
functionlogThis() {
console.log(this);
}
logThis();
Code language: JavaScript (javascript)
- function
- undefined
- Function.prototype
- window✔
Reference what is the javascript window
Q77. Which class-based component is equivalent to this function component?
constGreeting = ({ name }) => <h1>Hello {name}!</h1>;
Code language: JavaScript (javascript)
- 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>; } }
Q79. What is the output of this code?
var obj;
console.log(obj);
Code language: JavaScript (javascript)
- 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?
classTaxCalculator {
staticcalculate(total) {
return total * 0.05;
}
}
Code language: JavaScript (javascript)
- calculate(50);
- new TaxCalculator().calculate($50);
- TaxCalculator.calculate(50);✔
- new TaxCalculator().calculate(50);
Reference functions in javascript
Q81. What is wrong with this code?
const foo = {
bar() {
console.log('Hello, world!');
},
name: 'Albert',
age: 26,
};
Code language: JavaScript (javascript)
- 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.
- Nothing, there are no errors.✔
Q82. What will be logged to the console?
console.log('I');
setTimeout(() => {
console.log('love');
}, 0);
console.log('Javascript!');
Code language: JavaScript (javascript)
- A .✔
<strong>I
Javascript!
love
</strong>
Code language: HTML, XML (xml)
- B.
love
I
Javascript!
- C. The output may change with each execution of code and cannot be determined.
- D.
I
love
Javascript!
Reference https://developer.mozilla.org/en-US/docs/Web/API/setTimeout#reasons_for_delays_longer_than_specified especially see the ‘late timeouts’ section.
Q83. What will this code log to the console?
const foo = [1, 2, 3];
const [n] = foo;
console.log(n);
Code language: JavaScript (javascript)
- 1✔
- undefined
- NaN
- Nothing–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',
};
Code language: JavaScript (javascript)
- delete name from foo;
- delete foo.name;✔
- del foo.name;
- remove foo.name;
Reference working with objects
Q85. What is the difference between the map() and the forEach() methods on the Array prototype?
- There is no difference.
- The 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.✔
- The 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?
functionmakeAdder(x) {
returnfunction (y) {
return x + y;
};
}
var addFive = makeAdder(5);
console.log(addFive(3));
Code language: JavaScript (javascript)
- overloading
- closure
- currying✔
- overriding
Q87. Which tag pair is used in HTML to embed JavaScript?
- <script></script>✔
- <js></js>
- <javascript></javascript>
- <code></code>
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
- Access-Control-Allow-Origin✔
- Different-Origin
- Same-Origin
Reference Cross-Origin Resource Sharing
Q89. What is the output of this code?
let rainForests = ['Amazon', 'Borneo', 'Cerrado', 'Congo'];
rainForests.splice(0, 2);
console.log(rainForests);
Code language: JavaScript (javascript)
- [“Amazon”,”Borneo”,”Cerrado”,”Congo”]
- [“Cerrado”, “Congo”]✔
- [“Congo”]
- [“Amazon”,”Borneo”]
Q90. Which missing line would allow you to create five variables(one,two,three,four,five) that correspond to their numerical values (1,2,3,4,5)?
const numbers = [1, 2, 3, 4, 5];
<em>//MISSING LINE</em>
Code language: JavaScript (javascript)
- 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}
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);
Code language: JavaScript (javascript)
- Nothing, it will throw an error
- 0 2✔
- undefined 2
- undefined 2
Q92. Which line could you add to this code to print “jaguar” to the console?
let animals = ['jaguar', 'eagle'];
<em>//Missing Line</em>console.log(animals.pop()); <em>//Prints jaguar</em>
Code language: JavaScript (javascript)
- 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.
filter() – get every element in the array that meets the condition.
Q93. What line is missing from this code?
<em>//Missing Line</em>for (var i = 0; i < vowels.length; i++) {
console.log(vowels[i]);
<em>//Each letter printed on a separate line as follows;</em><em>//a</em><em>//e</em><em>//i</em><em>//o</em><em>//u</em>
}
Code language: JavaScript (javascript)
- let vowels = “aeiou”.toArray();
- let vowels = Array.of(“aeiou”);
- let vowels = {“a”, “e”, “i”, “o”, “u”};
- let vowels = “aeiou”;✔
Q94. What will be logged to the console?
const x = 6 % 2;
const y = x ? 'One' : 'Two';
console.log(y);
Code language: JavaScript (javascript)
- undefined
- One
- true
- Two✔
Note: 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"],["!","!","!"]];
Code language: JavaScript (javascript)
- 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');
Code language: JavaScript (javascript)
- It adds “Lizard” to the start of the animals array.✔
- It adds “Lizard” to the end of the animals array.
- It replaces “Rabbit” with “Lizard” in the animals array.
- It replaces “Cat” with “Lizard” in the animals array.
Q97. What is the output of this code?
let x = 6 + 3 + '3';
console.log(x);
Code language: JavaScript (javascript)
- 93✔
- 12
- 66
- 633
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?
- else
- when
- if
- switch✔
Q99. Which statement prints “roar” to the console?
var sound = 'grunt';
var bear = { sound: 'roar' };
functionroar() {
console.log(this.sound);
}
Code language: JavaScript (javascript)
- 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✔
Q101. Which statement correctly imports this code from some-file.js?
<em>//some-file.js</em>exportconstprintMe = (str) => console.log(str);
Code language: HTML, XML (xml)
- 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]);
Code language: JavaScript (javascript)
- [2, 3, 4, 5, 6, 7]
- [3,5,7,2,4,6]
- [3, 5, 7, 2, 4, 6]
- [[2, 4, 6], [3, 5, 7]]
- [2, 4, 6, 3, 5, 7]✔
Q103. Which method call is chained to handle a successful response returned by fetch()?
- done()
- then()✔
- finally()
- catch()
Q104. Which choice is not an array method?
- array.slice()
- array.shift()
- array.push()
- array.replace()✔
Q105. Which JavaScript loop ensures that at least a singular iteration will happen?
- do…while✔
- forEach
- while
- for
Q106. What will be logged to the console?
console.log(typeof'blueberry');
Code language: JavaScript (javascript)
- string✔
- array
- Boolean
- object
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>
Code language: HTML, XML (xml)
<em>//JavaScript</em>document.querySelectorAll('div').forEach((e) => {
e.onclick = (e) =>console.log(e.currentTarget.id);
});
Code language: JavaScript (javascript)
- C B A✔
- A
- C
- A B C
Q108. What will this code log to the console?
const myNumbers = [1, 2, 3, 4, 5, 6, 7];
constmyFunction = (arr) => {
return arr.map((x) => x + 3).filter((x) => x < 7);
};
console.log(myFunction(myNumbers));
Code language: JavaScript (javascript)
- [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. What does this code print to the console?
let rainForestAcres = 10;
let animals = 0;
while (rainForestAcres < 13 || animals <= 2) {
rainForestAcres++;
animals += 2;
}
console.log(animals);
Code language: JavaScript (javascript)
- 2
- 4
- 6✔
- 8
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 = '';
<em>/* Missing Snippet */</em>console.log(plainText); <em>//Prints YOU GOT THIS</em>
Code language: JavaScript (javascript)
- A
for (let key of cipherText.keys()) {
plainText += key % 2 === 0 ? key : ' ';
}
Code language: JavaScript (javascript)
- B
for (let [index, value] of cipherText.entries()) {
plainText += index % 2 !== 0 ? value : '';
}
Code language: JavaScript (javascript)
- C✔
<strong>for (let [index, value] of cipherText.entries()) {
plainText += index % 2 === 0 ? value : '';
}
</strong>
Code language: HTML, XML (xml)
- D
for (let value of cipherText) {
plainText += value;
}
Code language: JavaScript (javascript)
- Reference MDN JavaScript Destructuring
- Reference MDN JavaScript Array entries
- Reference MDN JavaScript Remainder/Modulo
Q111. Which Pokemon will be logged to the console?
var pokedex = ['Snorlax', 'Jigglypuff', 'Charmander', 'Squirtle'];
pokedex.pop();
console.log(pokedex.pop());
Code language: JavaScript (javascript)
- Charmander✔
- Jigglypuff
- Snorlax
- Squirtle
Explanation: The pop() method removes the last element from an array and returns that element. This method changes the length of the array.
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>
Code language: HTML, XML (xml)
- document.querySelector(“div.content”)
- document.querySelector(“span.content”)✔
- document.querySelector(“.content”)
- document.querySelector(“div.span”)
Q113. Which value is not falsely?
- []✔
- undefined
- 0
- null
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++;
Code language: JavaScript (javascript)
- line 5, because the 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 the result after running this code?
const person = { name: 'Dave', age: 40, hairColor: 'blue' };
const result = Object.keys(person).map((x) => x.toUpperCase());
Code language: JavaScript (javascript)
- 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 “swim” to the console?
let animals = ["eagle", "osprey", "salmon"];
letkey = animal => animal === "salmon";
if(<em>/* Insert Snippet Here */</em>){
console.log("swim");
}
Code language: JavaScript (javascript)
- animals.every(key)
- animals.some(key).length === 1
- animals.filter(key) === true
- animals.some(key)✔
Reference Array.prototype.some
Q117. What is the output of this code?
classRainForest {
static minimumRainFall = 60;
}
let congo = newRainForest();
RainForest.minimumRainFall = 80;
console.log(congo.minimumRainFall);
Code language: JavaScript (javascript)
- undefined✔
- None of these answers, as static is not a feature in Javascript.
- 60
- 80
Q118. How can you attempt to access the property a.b on obj without throwing an error if a is undefined?
let obj = {};
Code language: JavaScript (javascript)
- 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);
Code language: JavaScript (javascript)
- It will throw a ReferenceError about
x
. - It will print 18.
- It will print undefined.
- It will throw a ReferenceError about y.✔
Q120. What does this code print to the console?
const x = [1, 2];
const y = [5, 7];
const z = [...x, ...y];
console.log(z);
Code language: JavaScript (javascript)
- [1,2,5,7]✔
- [[1, 2], [5, 7]]
- [2,7]
- [2,1,7,5]
Q121. Given this code, which statement will be evaluated as false?
const a = { x: 1 };
const b = { x: 1 };
Code language: JavaScript (javascript)
- a[‘x’] === b[‘x’]
- a != b
- a === b✔
- a.x === b.x
Q122. What will this code log to the console?
console.log(typeof41.1);
Code language: CSS (css)
- Nothing. It results in a ReferenceError.
- decimal
- float
- number✔
Q123. What is the output of this code?
let scores = [];
scores.push(1, 2);
scores.pop();
scores.push(3, 4);
scores.pop();
score = scores.reduce((a, b) => a + b);
console.log(score);
Code language: JavaScript (javascript)
- 3
- 4✔
- 6
- 7
Q124. What does this code print to the console?
let bear = {
sound: 'roar',
roar() {
console.log(this.sound);
},
};
bear.sound = 'grunt';
let bearSound = bear.roar;
bearSound();
Code language: JavaScript (javascript)
- Nothing is printed to the console.
- grunt
- undefined✔
- roar
Q125. What is the output of this code?
var cat = { name: 'Athena' };
functionswap(feline) {
feline.name = 'Wild';
feline = { name: 'Tabby' };
}
swap(cat);
console.log(cat.name);
Code language: JavaScript (javascript)
- undefined
- Wild✔
- Tabby
- Athena
Q126. What will this code output to the log?
var thing;
letfunc = (str = 'no arg') => {
console.log(str);
};
func(thing);
func(null);
Code language: JavaScript (javascript)
- null no arg
- no arg no arg
- null null
- no arg null✔
Q127. What will this code print to the console?
constmyFunc = () => {
const a = 2;
return() =>console.log('a is ' + a);
};
const a = 1;
const test = myFunc();
test();
Code language: JavaScript (javascript)
- a is 1
- a is undefined
- It won’t print anything.
- a is 2✔
Q128. What will this code print to the console?
constmyFunc = (num1, num2 = 2, num3 = 2) => {
return num1 + num2 + num3;
};
let values = [1, 5];
const test = myFunc(2, ...values);
console.log(test);
Code language: JavaScript (javascript)
- 8✔
- 6
- 2
- 12
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);
Code language: JavaScript (javascript)
- 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 (<em>/* Snipped goes here */</em>){
++acresOfRainForest;
}
Code language: JavaScript (javascript)
- conservation && !deforestation✔
- !deforestation && !conservation
- !conservation || deforestation
- deforestation && conservation || deforestation
Q131. Which of these evaluate to be true?
- Boolean(“false”)✔
- Boolean(“”)
- Boolean(0)
- Boolean(NaN)
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”);
Q133. What value is printed to the console after this code executes?
let cat = Object.create({ type: 'lion' });
cat.size = 'large';
let copyCat = { ...cat };
cat.type = 'tiger';
console.log(copyCat.type, copyCat.size);
Code language: JavaScript (javascript)
- tiger large
- lion undefined
- undefined large✔
- lion large
Q134. What does this code print to the console?
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]);
Code language: JavaScript (javascript)
- bear bear tiger sheep✔
- lion bear sheep sheep
- bear bear tiger tiger
- lion bear tiger sheep
Q135. What will be the output of the following code?
a=5;
b=4;
alert(a++(+(+(+b))));
- 18
- 10
- 9✔
- 20
Q136. Which snippet could you add to this code to print “{“type”: “tiger”}” to the console?
let cat = { type: "tiger", size: "large" };
let json = <em>/* Snippet here */</em>;
console.log(json); <em>// print {"type":"tiger"}</em>
Code language: JavaScript (javascript)
- cat.toJSON(“type”);
- JSON.stringify(cat, [“type”]);✔
- JSON.stringify(cat);
- JSON.stringify(cat, /type/);
Q137. Which document method is not used to get a reference to a DOM node?
- document.getNode();✔
- document.getElementsByClassName();
- document.querySelectorAll();
- document.querySelector();
Q138. In JavaScript, all objects inherit a built-in property from a ___.
- node
- instance variable
- prototype✔
- accessor
Q139. Which of the following are not server-side Javascript objects?
- Date
- FileUpload✔
- Function
- All of the above
Q140. What will be the output of the following code snippet?
const obj1 = { first: 20, second: 30, first: 50 };
console.log(obj1);
Code language: JavaScript (javascript)
- first: 30 , second: 50
- first: 50 , second: 30✔
- first: 30 , second: 20
- None of the above
Q141. Which object in Javascript doesn’t have a prototype?
- Base Object✔
- All objects have a prototype
- None of the objects have a prototype
- None of the above
Q142. What does … operator do in JS?
- Used to spread iterables to individual elements✔
- Describe the datatype of the 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
Q144. What will be the output of the following code snippet?
print(typeofNaN);
Code language: PHP (php)
- Object
- Number✔
- String
- 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>
Code language: HTML, XML (xml)
- 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 the total after this code executes?
functionsum(num1, num2 = 2, num3 = 3) {
return num1 + num2 + num3;
}
let values = [1, 5];
let total = sum(4, ...values);
Code language: JavaScript (javascript)
- 10✔
- 6
- 7
- 8
Q148. Which statement applies to the defer attribute of the HTML <script> tag?
- 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.
Reference: defer html script attribute
Q149. Which method of a class is called to initialize an object of that class?
- init()
- create()
- new()
- constructor()✔
Q150. Which expression evaluates to true?
- Boolean(NaN)
- Boolean(0)
- Boolean(“false”)✔
- Boolean(“”)
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”.contains(“pot”);
Reference: String.prototype.includes()
Q152. Which collection object allows a unique value to be inserted only once?
- Map
- Array
- Set✔
- Object
Reference: developer.mozilla Set
Q153. How would you change the color of this header to pink?
<strong><h2 id="cleverest">girls</h2></strong>
Code language: HTML, XML (xml)
- document.getElementByName(“cleverest”).style.color = “pink”;
- document.getElementsByTagName(“h2”).style.color = “pink”;
- document.getElementByName(“h2”).style.color = “pink”;
- document.getElementById(“cleverest”).style.color = “pink”;✔
Reference: W3Schools HTML DOM Style color Property
Q154. Which line is missing from this code if you expect the code to evaluate to true?
<strong>var compare = function (test1, test2) {
// Missing line
};
compare(1078, '1078'); // yields true</strong>
Code language: JavaScript (javascript)
-
test1==test2;
- return test1===test2;
- return test1==test2;✔
- return test1!=test2;
Q155. What is the output of this code?
<strong>if (true) { </strong>
<strong>var first = 'You'; </strong>
<strong>} </strong>
<strong>function fScope() { </strong>
<strong>var second = 'got this!'; </strong>
<strong>} </strong>
<strong>fScope(); </strong>
<strong>console.log(first); </strong>
<strong>console.log(second);</strong>
Code language: HTML, XML (xml)
- You
undefined - You
ReferenceError✔ - undefined
undefined - You
got this!
Reference: W3schools JS Scoping
Q156. What is the output for the code given below?
<strong>console.log('hello' + 'world');</strong>
Code language: JavaScript (javascript)
- helloworld!✔
- helloworld !
- hello world!
- hello world !
Q157. What is the output of this code?
<strong>console.log(10 + 10);</strong>
Code language: HTML, XML (xml)
- 10
- 20✔
- 30
- 40
Q158. Events related to the browser window can be handled by?
- Onclicks
- Window✔
- querySelector
- None of the above
Q159. How do you define a function in JavaScript?
- function myFunction() {}✔
- def myFunction() {}
- var myFunction = () => {}
- func myFunction() {}
Q160. 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 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
- function
Q164. What function is used in JavaScript to schedule a function to run after a specified number of milliseconds?
- setTimeout()✔
- setInterval()
- delay()
- wait()
Q165. Which of the following is a server-side JavaScript object?
- Function
- File✔
- FileUpload
- Date
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?
<strong>const foo = () => console.log('First'); const bar = () => setTimeout(() => console.log('Second'), 0); foo(); bar(); console.log('Third');</strong>
Code language: JavaScript (javascript)
- Second, First, Third
- First, Third, Second✔
- First, Second, Third
- Third, First, Second
Q168. What will be the output of running this code?
<strong>function scream(words) { return words.toUpperCase() + '!!!'; } scream('yay');</strong>
Code language: JavaScript (javascript)
- YAY!!!
- ReferenceError
- Undefined✔
- TypeError