Best Tips To Pass Salesforce Certified JavaScript Developer I Exam

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Do you want to pass Salesforce Certified JavaScript Developer I exam? JavaScript Developer I exam is intended for individuals who have the knowledge, skills, and experience developing front-end and/or back-end JavaScript applications for the web stack. JavaScript Developer I Exam Dumps are available with actual dumps questions and answers for good preparation. FreeTestShare always keeps candidates up to date with the JavaScript Developer I exam areas. Anyone who has registered with JavaScript Developer I Dumps gets exclusive access to the updated version of all the valid exam questions.

You should try JavaScript Developer I practice test questions to assess yourself.

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1. A test has a dependency on database.query. During the test the dependency is replaced with an object called database with the method, query, that returns an array. The developer needs to verify how many times the method was called and the arguments used each time.

Which two test approaches describe the requirement? Choose 2 answers

Integration

Black box

White box

Mocking

2. Refer to the code snippet:

Function getAvailabilityMessage(item) {

If (getAvailability(item)){

Var msg =”Username available”;

}

Return msg;

}

A developer writes this code to return a message to user attempting to register a new username. If the username is available, variable.

What is the return value of msg hen getAvailabilityMessage (“newUserName” ) is executed and getAvailability(“newUserName”) returns false?

“Username available”

“newUserName”

“Msg is not defined”

undefined

3. 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?

window.history.pushState(newStateObject);

window.history.pushStare(newStateObject, '', null);

window.history.replaceState(newStateObject,'', null);

window.history.state.push(newStateObject);

4. A developer creates a simple webpage with an input field. When a user enters text in the input field and clicks the button, the actual value of the field must be displayed in the console.

Here is the HTML file content:

<input type =” text” value=”Hello” name =”input”>

<button type =”button” >Display </button>

The developer wrote the javascript code below:

Const button = document.querySelector(‘button’);

button.addEvenListener(‘click’, () => (

Const input = document.querySelector(‘input’);

console.log(input.getAttribute(‘value’));

When the user clicks the button, the output is always “Hello”.

What needs to be done make this code work as expected?

Replace line 04 with console.log(input .value);

Replace line 03 with const input = document.getElementByName(‘input’);

Replace line 02 with button.addEventListener(“onclick”, function() {

Replace line 02 with button.addCallback(“click”, function() {

5. 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) …`);

07 )

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 . . .

Console16bit.prototype.load(gamename) = function() {

Console16bit.prototype.load = function(gamename) {

Console16bit = Object.create(GameConsole.prototype).load = function (gamename) {

Console16bit.prototype.load(gamename) {

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

True + ‘13’ + NaN

‘ 113Nan ’

‘ true13 ’

‘ true13NaN ’

7. Refer to code below:

Let first = ‘who’;

Let second = ‘what’;

Try{

Try{

Throw new error(‘Sad trombone’);

}catch (err){

First =’Why’;

}finally {

Second =’when’;

} catch (err) { Second =’Where’;

}

What are the values for first and second once the code executes?

First is Who and second is When

First is why and second is where

First is who and second is where

First is why and second is when

8. 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

console.assert(sum3(1, ‘2’)) == 12);

console.assert(sum3(0)) == 0);

console.assert(sum3(-3, 2 )) == -1);

console.assert(sum3(‘hello’, 2, 3, 4)) === NaN);

9. Given code below:

setTimeout (() => (

console.log(1);

). 0);

console.log(2);

New Promise ((resolve, reject )) = > (

setTimeout(() => (

reject(console.log(3));

). 1000);

)).catch(() => (

console.log(4);

));

console.log(5);

What is logged to the console?

2 1 4 3 5

2 5 1 3 4

1 2 4 3 5

1 2 5 3 4

10. Refer to the code snippet below:

What is the value of array after the code executes?

[1, 2, 3, 4, 5, 4, 4]

[1, 2, 3, 4, 4, 5, 4]

[1, 2, 3, 5]

[1, 2, 3, 4, 5, 4]

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11. Which three browser specific APIs are available for developers to persist data between page loads? Choose 3 answers

IIFEs

indexedDB

Global variables

localStorage.

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

The associated class contains some asynchronous functions.

The associated function will always return a promise

The associated function can only be called via asynchronous methods

The associated sometimes returns a promise.

13. Which statement phrases successfully?

JSO

parse ( ‘ foo ’ );

JSO

parse ( “ foo ” );

JSO

parse( “ ‘ foo ’ ” );

JSO

parse(‘ “ foo ” ’);

14. 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

White box

Stubbing

Black box

Substitution

15. Given the code below:

Setcurrent URL ();

console.log(‘The current URL is: ‘ +url );

function setCurrentUrl() {

Url = window.location.href:

What happens when the code executes?

The url variable has local scope and line 02 throws an error.

The url variable has global scope and line 02 executes correctly.

The url variable has global scope and line 02 throws an error.

The url variable has local scope and line 02 executes correctly.

16. Refer to the code below:

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

> true > false

> 5 >undefined

> 5 > -1

> 5 > 0

17. 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

const addBy = function(num1){ return function(num2){ return num1 + num2; }

const addBy = function(num1){ return num1 + num2; }

const addBy = (num1) => num1 + num2 ;

const addBY = (num1) => (num2) => num1 + num2;

18. Given the code below:

Which method can be used to provide a visual representation of the list of users and to allow sorting by the name or email attribute?

console.group(usersList) ;

console.table(usersList) ;

console.info(usersList) ;

console.groupCol lapsed (usersList) ;

19. Refer to the code below:

Const myFunction = arr => {

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

Return result = current;

}, 10};

}

What is the output of this function when called with an empty array?

Returns 0

Throws an error

Returns 10

Returns NaN

20. 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

Vue

Angular

Koa

Express

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21. A developer has code that calculates a restaurant bill, but generates incorrect answers while testing the code:

function calculateBill ( items ) {

let total = 0;

total += findSubTotal(items);

total += addTax(total);

total += addTip(total);

return total;

}

Which option allows the developer to step into each function execution within calculateBill?

Using the debugger command on line 05.

Using the debugger command on line 03

Calling the console.trace (total) method on line 03.

Wrapping findSubtotal in a console.log() method.

22. 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?

01 let monthName =’July’;

02 let year =2019;

02 const year = 2020;

03 if (year == 2019) {

23. Given the code below:

const copy = JSON.stringify([ new String(‘ false ’), new Bollean( false ), undefined ]);

What is the value of copy?

-- [ ”false” , { } ]--

-- [ false, { } ]--

-- [ ”false” , false, undefined ]--

-- [ ”false” ,false, null ]--

24. 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?

1.3.1

1.3.5

The command fails, because version 130 is not found

1.4.0

25. Refer to the code below:

Const pi = 3.1415326,

What is the data type of pi?

Double

Number

Decimal

Float

26. 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

The line 02 assertion passes.

The line 02 assertion fails

The line 05 assertion passes.

The line 05 assertion fails.

27. Refer to the expression below:

Let x = (‘1’ + 2) == (6 * 2);

How should this expression be modified to ensure that evaluates to false?

Let x = (‘1’ + ‘ 2’) == ( 6 * 2);

Let x = (‘1’ + 2) == ( 6 * 2);

Let x = (1 + 2) == ( ‘6’ / 2);

Let x = (1 + 2 ) == ( 6 / 2);

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

const retrieveFromLocalStorage = () =>{ return JSO

stringify(window.localStorage.getItem(storageKey)); }

const retrieveFromLocalStorage = (storageKey) =>{ return window.localStorage.getItem(storageKey); }

const retrieveFromLocalStorage = (storageKey) =>{ return JSO

parse(window.localStorage.getItem(storageKey)); }

const retrieveFromLocalStorage = (storageKey) =>{ return window.localStorage[storageKey]; }

29. A developer is working on an ecommerce website where the delivery date is dynamically calculated based on the current day. The code line below is responsible for this calculation.

Const deliveryDate = new Date ();

Due to changes in the business requirements, the delivery date must now be today’s

date + 9 days.

Which code meets this new requirement?

deliveryDate.setDate(( new Date ( )).getDate () +9);

deliveryDate.setDate( Date.current () + 9);

deliveryDate.date = new Date(+9) ;

deliveryDate.date = Date.current () + 9;

30. Refer to the code below?

Let searchString = ‘ look for this ’;

Which two options remove the whitespace from the beginning of searchString? Choose 2 answers

searchString.trimEnd();

searchString.trimStart();

trimStart(searchString);

searchString.replace(/*ss*/, ‘’);

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31. A developer is wondering whether to use, Promise.then or Promise.catch, especially when a Promise throws an error?

Which two promises are rejected?

Which 2 are correct?

Promise.reject(‘cool error here’).then(error => console.error(error));

Promise.reject(‘cool error here’).catch(error => console.error(error));

New Promise((resolve, reject) => (throw ‘cool error here’}).catch(error => console.error(error)) ;

New Promise(() => (throw ‘cool error here’}).then(null, error => console.error(error)));

32. Universal Container (UC) just launched a new landing page, but users complain that the website is slow. A developer found some functions that cause this problem. To verify this, the developer decides to do everything and log the time each of these three suspicious functions consumes.

console.time(‘Performance’);

maybeAHeavyFunction();

thisCouldTakeTooLong();

orMaybeThisOne();

console.endTime(‘Performance’);

Which function can the developer use to obtain the time spent by every one of the three functions?

console.timeLog()

console.getTime()

console.trace()

console.timeStamp()

33. Which three options show valid methods for creating a fat arrow function? Choose 3 answers

x => ( console.log(‘ executed ’) ; )

[ ] => ( console.log(‘ executed ’) 😉

( ) => ( console.log(‘ executed ’) 😉

X,y,z => ( console.log(‘ executed ’) 😉

(x,y,z) => ( console.log(‘ executed ’) 😉

34. 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?

Class ClothingItem implements Item{

Class ClothingItem {

Class ClothingItem super Item {

Class ClothingItem extends Item {

35. 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?

Inner function’s scope

Hoisting

Outer function’s scope

Prototype chain

36. Refer to following code:

class Vehicle {

constructor(plate) {

This.plate =plate;

}

}

Class Truck extends Vehicle {

constructor(plate, weight) {

//Missing code

This.weight = weight;

}

displayWeight() {

console.log(‘The truck ${this.plate} has a weight of ${this.weight} lb.’);}} Let myTruck = new Truck(‘123AB’, 5000); myTruck.displayWeight();

Which statement should be added to line 09 for the code to display ‘The truck 123AB has a weight of 5000lb.’?

Super.plate =plate;

super(plate);

This.plate =plate;

Vehicle.plate = plate;

37. 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?

End Start Success

Start Success End

Start End Success

Success Start End

38. A developer wrote a fizzbuzz function that when passed in a number, returns the following:

‘Fizz’ if the number is divisible by 3.

‘Buzz’ if the number is divisible by 5.

‘Fizzbuzz’ if the number is divisible by both 3 and 5.

Empty string if the number is divisible by neither 3 or 5.

Which two test cases will properly test scenarios for the fizzbuzz function? Choose 2 answers

let res = fizzbuzz(5); console.assert ( res === ‘ ’ );

let res = fizzbuzz(15); console.assert ( res === ‘ fizzbuzz ’ )

let res = fizzbuzz(Infinity); console.assert ( res === ‘ ’ )

let res = fizzbuzz(3); console.assert ( res === ‘ buzz ’ )

39. 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

The line 05 assertion passes.

The line 02 assertion passes.

The line 02 assertion fails.

The line 05 assertion fails.

40. developer has a web server running with Node.js. The command to start the web server is node server,js. The web server started having latency issues. Instead of a one second turn around for web requests, the developer now sees a five second turnaround,

Which command can the web developer run to see what the module is doing during the latency period?

DEBUG = http, https node server.js

NODE_DEBUG =http, https node server.js

DEBUG =true node server.js

NODE_DEBUG =true node server.js

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41. Refer to the following code:

<html lang=”en”>

<body>

<div onclick = “console.log(‘Outer message’) ;”>

<button id =”myButton”>CLick me<button>

</div>

</body>

<script>

function displayMessage(ev) {

ev.stopPropagation();

console.log(‘Inner message.’);

}

const elem = document.getElementById(‘myButton’);

elem.addEventListener(‘click’ , displayMessage);

</script>

</html>

What will the console show when the button is clicked?

Outer message

Outer message Inner message

Inner message Outer message

Inner message

42. 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?

Const sum = curr.startsWith(‘N’)? 1: 0; Return acc +sum

Const sum = curr.name.startsWith(‘N’)? 1: 0; Return acc +sum

Const sum = curr.startsWIth(‘N’)? 1: 0; Return curr+ sum

Const sum = curr.name.startsWIth(‘N’)? 1: 0; Return curr+ sum

43. 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?

Replace line 02 with return arr.map(( result, current) => (

Replace line 04 with result = result +current;

Replace line 03 with if(arr.length == 0 ) ( return 0; )

Replace line 05 with return result;