JAVASCRIPT-DEVELOPER-I Online Practice Questions and Answers

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 bedisplayed in the console.

Here is the HTML file content:

Display 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 to make this code work as expected?

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

B. Replace line 03 with const input = document.getElementByName(`input');

C. Replace line 02 with button.addCallback("click", function() {

D. Replace line 02 with button.addEventListener("onclick", function() {

Given the code below:

Function myFunction(){

A =5;

Var b =1;

}

myFunction();

console.log(a);

console.log(b);

What is the expected output?

A. Both lines 08 and 09 are executed, and the variables are outputted.

B. Line 08 outputs the variable, but line 09 throws an error.

C. Line 08 thrones an error, therefore line 09 is never executed.

D. Both lines 08 and 09 are executed, but values outputted are undefined.

Which function should a developer use to repeatedly execute code at a fixed interval ?

A. setIntervel

B. setTimeout

C. setPeriod

D. setInteria

Refer to the code below:

Let str = `javascript';

Str[0] = `J';

Str[4] = 'S';

After changing the stringindex values, the value of str is `javascript'. What is the reason

for this value:

A. Non-primitive values are mutable.

B. Non-primitive values are immutable.

C. Primitive values are mutable.

D. Primitive values are immutable.

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

The Code shown Below:

ClassPost {

// Insert code here

This.body =body

This.author = author;

this.viewCount = viewCount;

}

}

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

A. super (body, author, viewCount) {

B. Function Post (body, author, viewCount) {

C. constructor (body, author, viewCount) {

D. constructor() {

Refer to the code below:

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

Which two statements result in the array [1, 2, 3, 4, 5] ?

Choose 2 answers

A. [ ]. Concat.apply ([ ], inArray);

B. []. Concat (... inArray);

C. [ ]. concat.apply(inArray, [ ]);

D. [ ]. concat ( [ ....inArray ] );

Refer to the code below:

Function changeValue(obj) {

Obj.value =obj.value/2;

}

Const objA = (value: 10);

Const objB = objA;

changeValue(objB);

Const result = objA.value;

What is the value of result after the code executes?

A. 10

B. Nan

C. 5

D. Undefined

A developer copied a JavaScript object:

How does the developer access dan's forstName,lastName? Choose 2 answers

A. dan,name

B. dan,firstname ( ) + dan, lastName ( )

C. dan, firstName = dan.lastName

D. dan,name ( )

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);

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

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

C. Return Integer(num +10) /3;

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

Given the JavaScript below:

Which code should replace the placeholder comment on line 06 to hide accounts that do not match the search string?

A. `None' : `block'

B. `Visible : 'hidden'

C. `Hidden, visible

D. `Block' : `none'