Real JavaScript-Developer-I Exam Questions are the Best Preparation Material [Q54-Q72]

admin JavaScript-Developer-I Salesforce May 14, 2023

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Real JavaScript-Developer-I Exam Questions are the Best Preparation Material

Practice on 2023 LATEST JavaScript-Developer-I Exam Updated 225 Questions

NEW QUESTION 54
Which option is true about the strict mode in imported modules?

Add the statement use non-strict, before any other statements in the module to enable
not-strict mode.

You can only reference notStrict() functions from the imported module.

Imported modules are in strict mode whether you declare them as such or not.

Add the statement use strict =false; before any other statements in the module to enable
not- strict mode.

NEW QUESTION 55
A developer has the following array of student test grades:
Let arr = [ 7, 8, 5, 8, 9 ];
The Teacher wants to double each score and then see an array of the students who scored more than 15 points.
How should the developer implement the request?

Let arr1 = arr.filter(( val) => ( return val > 15 )) .map (( num) => ( return num *2 ))

Let arr1 = arr.mapBy (( num) => ( return num *2 )) .filterBy (( val ) => return val > 15 )) ;

Let arr1 = arr.map((num) => num*2). Filter (( val) => val > 15);

Let arr1 = arr.map((num) => ( num *2)).filterBy((val) => ( val >15 ));

NEW QUESTION 56
Given the following code:

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

Event, clicked

Event,target.nodename == ‘BUTTON”

o.nodeTarget == this

button.addEventListener ( ‘click’)

NEW QUESTION 57
Given the following code:
let x = null;
console.log(typeof x);
What is the output?

“object”

“undefined”

“null”

“x”

NEW QUESTION 58
Given the requirement to refactor the code above to JavaScript class format, which class definition is correct?

NEW QUESTION 59
Refer to the code snippet below:
Let array = [1, 2, 3, 4, 4, 5, 4, 4];
For (let i =0; i < array.length; i++)
if (array[i] === 4) {
array.splice(i, 1);
}
}
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]

NEW QUESTION 60
Refer to the code below:
For (let number =2: number <= S; number += 1) ( // insert code statement here The developer needs to insert a code statement in the location shown. The code statement has these requirements:
1. Does not require an import
2. Logs an error when the Boolean statement evaluates to false
3. Works In both the browser and Node.js
Which statement meet these requirements?

Assert (number $ 2 == 0);

Console. error (number $ 2 == 0) ;

Console. Debug (number $ 2 == 0) ;

Console. Assert ( number $ 2 == 0 ) ;

NEW QUESTION 61
Given the expressions var1 and var2, what are two valid ways to return the concatenation of the two expressions and ensure it is string? Choose 2 answers

var1 + var2

var1.toString ( ) var2.toString ( )

String (var1) .concat (var2)

string.concat (var1 +var2)

NEW QUESTION 62
A developer is asked to fix some bugs reported by users. To do that, the developer adds a breakpoint for debugging.

When the code execution stops at the breakpoint on line 06, which two types of information are available In the browser console? Choose 2 answers

The value of the carSpeed and fourWheel variables

A variable’s displaying the number of instances created for the Car object.

The style, event listeners and other attributes applied to the carSpeed DOM element.

The information stored in the window.localStorage property.

NEW QUESTION 63
A developer is creating a simple webpage with a button. When a user clicks this button for the first time, a message is displayed.
The developer wrote the JavaScript code below, but something is missing. The message gets displayed every time a user clicks the button, instead of just the first time.
01 function listen(event) {
02 alert ( ‘Hey! I am John Doe’) ;
03 button.addEventListener (‘click’, listen);
Which two code lines make this code work as required?
Choose 2 answers

On line 02, use event.first to test if it is the first execution.

On line 04, use event.stopPropagation ( ),

On line 04, use button.removeEventListener(‘ click” , listen);

On line 06, add an option called once to button.addEventListener().

NEW QUESTION 64
Refer to the following code that performs a basic mathematical operation on a provided input:
function calculate(num) {
Return (num +10) / 3;
}
How should line 02 be written to ensure that x evaluates to 6 in the line below?
Let x = calculate (8);

Return Number((num +10) /3 );

Return (Number (num +10 ) / 3;

Return Integer(num +10) /3;

Return Number(num + 10) / 3;

NEW QUESTION 65
Refer to the following code:

Which two statement could be inserted at line 17 to enable the function call on line 18?
Choose 2 answers

Object.assign (leo, tony);

Object.assign (leo. Tiger);

leo.roar = () => { console.log(‘They’re pretty good!’); );

leo.prototype.roar = ( ) =>( console.log(‘They’re pretty good!’); };

NEW QUESTION 66
A 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 turnaround 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?

NODE_DEBUG=true node server.js

DEBUG=http, https node server.js

NODE_DEBUG=http,https node server.js

DEBUG=true node server.js

NEW QUESTION 67
Refer to code below:
function Person() {
this.firstName = ‘John’;
}
Person.prototype ={
Job: x => ‘Developer’
};
const myFather = new Person();
const result =myFather.firstName + ‘ ‘ + myFather.job();
What is the value of the result after line 10 executes?

Error: myFather.job is not a function

Undefined Developer

John undefined

John Developer

NEW QUESTION 68
The developer wants to test the array shown:
Const arr = Array (5) . fill (0);
Which two test are the most accurate for this array? Choose 2 answers

Console,assert(arr.length === 5) ;

Arr. forEach (elem => console .assert (elem === 0) );

Console,assert(arr(0) === 0 $$ arr (arr .longth ) === 0) ;

Console. Assert (arr. Length > 0) ;

NEW QUESTION 69
Refer to the following array:
Let arr1 = [ 1, 2, 3, 4, 5 ];

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

Let arr2 = arr1.slice(0, 5);

Let arr2 = Array.from(arr1);

Let arr2 = arr1;

Let arr2 = arr1.sort();

NEW QUESTION 70
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);

NEW QUESTION 71
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) {

NEW QUESTION 72
Refer to code below:
Function muFunction(reassign){
Let x = 1;
var y = 1;
if( reassign ) {
Let x= 2;
Var y = 2;
console.log(x);
console.log(y);}
console.log(x);
console.log(y);}
What is displayed when myFunction(true) is called?

2 2 1 1

2 2 undefined undefined

2 2 1 2

2 2 2 2

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