Prepare for Salesforce JavaScript Developer I Certification - Mock Test 2

Question 1 of 20

Given the code below:

const copy = JSON.stringify([new String('false'), new Boolean(false), undefined]);

What is the value of `copy`?

Choose 1 answer

A. '["false", false, undefined]'

B. '[false, {}]'

C. '["false", {}]'

D. '["false", false, null]'

Question 2 of 20

A team at Universal Containers works on a big project and uses Yarn to manage the project's dependencies. A developer added a dependency to manipulate dates and pushed the updates to the remote repository. The rest of the team complains that the dependency does not get downloaded when they execute Yarn. What could be the reason for this?

Choose 1 answer

A. The developer added the dependency as a dev dependency, and YARN_ENV is set to production.

B. The developer added the dependency as a dev dependency, and NODE_ENV is set to production.

C. The developer missed the option --add when adding the dependency.

D. The developer missed the option --save when adding the dependency.

Question 3 of 20

Which statement accurately describes the behavior of the async/await keywords?

Choose 1 answer

A. The associated class contains some asynchronous functions.

B. The associated function can only be called via asynchronous methods.

C. The associated function is asynchronous, but acts like synchronous code.

D. The associated function sometimes returns a promise.

Question 4 of 20

Refer to the following code block:

01 let array = [1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11];
02 let output = 0;
03
04 for (let num of array) {
05   if (output > 10)
06     break;
07   if (num % 2 == 0)
08     continue;
09   output += num;
10 }

What is the value of `output` after the code executes?

Choose 1 answer

A. 16

B. 11

C. 25

D. 36

Question 5 of 20

Given the JavaScript below:

01 function filterDOM(searchString) {
02   const parsedSearchString = searchString && searchString.toLowerCase();
03   document.querySelectorAll('.account').forEach(account => {
04     const accountName = account.innerHTML.toLowerCase();
05     account.style.display = accountName.includes(parsedSearchString)
06       ? /* Insert code here */
07       : 'none';
08   });
09 }

Which code should replace the placeholder comment on line 05 to hide accounts that do not match the search string?

Choose 1 answer

A. 'none' : 'block'

B. 'visible' : 'hidden'

C. 'block' : 'none'

D. 'hidden' : 'visible'

Question 6 of 20

Given the following code:

01 let x = null;
02 console.log(typeof x);

What is the output of line 02?

Choose 1 answer

A. 'undefined'

B. 'object'

C. 'null'

D. 'x'

Question 7 of 20

Refer to the code below:

01 let sayHello = () => {
02   console.log('Hello, World!');
03 };

Which code executes `sayHello` once, two minutes from now?

Choose 1 answer

A. delay(sayHello, 120000);

B. setInterval(sayHello, 120000);

C. setTimeout(sayHello, 120000);

D. setTimeout(sayHello(), 120000);

Question 8 of 20

Refer to the code below:

01 const objBook = {
02   title: 'JavaScript'
03 };
04 Object.preventExtensions(objBook);
05 const newObjBook = objBook;
06 newObjBook.author = 'Robert';

What are the values of `objBook` and `newObjBook` respectively?

Choose 1 answer

A. { author: 'Robert', title: 'JavaScript' } { author: 'Robert', title: 'JavaScript' }

B. { author: 'Robert' } { author: 'Robert', title: 'JavaScript' }

C. { title: 'JavaScript' } { title: 'JavaScript' }

D. { author: 'Robert', title: 'JavaScript' } undefined

Question 9 of 20

Which statement accurately describes an aspect of promises?

Choose 1 answer

A. then() cannot be added after a catch.

B. In a then() function, returning results is not necessary since callbacks will catch the result of a previous promise.

C. then() manipulates and returns the original promise.

D. Arguments for the callback function passed to then() are optional.

Question 10 of 20

Refer to the code below:

01 let array = [1, 2, 3, 4, 4, 5, 4, 4];
02 for (let i = 0; i < array.length; i++) {
03   if (array[i] === 4) {
04     array.splice(i, 1);
05   }
06 }

What is the value of `array` after the code executes?

Choose 1 answer

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

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

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

D. [1, 2, 3, 5]

Question 11 of 20

Refer to the code below:

01 let array = [1, 2, 3, 4, 4, 5, 4, 4];
02 for (let i = 0; i < array.length; i++) {
03   if (array[i] === 4) {
04     array.splice(i, 1);
05   }
06 }

What is the value of `array` after the code executes?

Choose 1 answer

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

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

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

D. [1, 2, 3, 5]

Question 12 of 20

A developer tries to retrieve all cookies, then sets a certain key-value pair in the cookie. These statements are used:

01 document.cookie;
02 document.cookie = 'key=John Smith';

What is the behavior?

Choose 1 answer

A. Cookies are read and the key value is set, and all cookies are wiped.

B. Cookies are read, but the key value is not set because the value is not URL encoded.

C. Cookies are not read because line 01 should be document.cookies, but the key value is set and all cookies are wiped.

D. Cookies are read and the key value is set, the remaining cookies are unaffected.

Question 13 of 20

Refer to the code below:

01 const addBy = ?;
02 const addByEight = addBy(8);
03 const sum = addByEight(50);

Which functions can replace line 01 and return 58 to sum?

Choose 2 answers

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

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

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

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

Question 14 of 20

Given a value, which three options can a developer use to detect if the value is NaN?

Choose 3 answers

A. value == NaN

B. Object.is(value, NaN)

C. value === Number.NaN

D. Number.isNaN(value)

E. value !== value

Question 15 of 20

A developer has the function, shown below, that is called when a page loads.

function onload() {
  console.log('Page has loaded!');
}

Where can the developer see the log statement after loading the page in the browser?

Choose 1 answer

A. In the browser performance tools log

B. On the terminal console running the web server

C. On the webpage console log

D. On the browser JavaScript console

Question 16 of 20

Refer to the string below:

const str = 'Salesforce';

Which statements result in the word 'Sales'?

Choose 2 answers

A. str.substring(0, 5);

B. str.substr(0, 5);

C. str.substring(1, 5);

D. str.substr(1, 5);

Question 17 of 20

Refer to the code below:

01 async function functionUnderTest(isOK) {
02   if (isOK) return 'OK';
03   throw new Error('not OK');
04 }

Which assertion accurately tests the above code?

Choose 1 answer

A. console.assert(await functionUnderTest(true), 'not OK');

B. console.assert(functionUnderTest(true), 'OK');

C. console.assert(await functionUnderTest(true), 'not OK');

D. console.assert(await functionUnderTest(true), 'OK');

Question 18 of 20

What are two unique features of functions defined with a fat arrow as compared to normal function definition?

Choose 2 answers

A. The function uses the this from the enclosing scope.

B. The function receives an argument that is always in scope, called parent this, which is the enclosing lexical scope.

C. If the function has a single expression in the function body, the expression will be evaluated and implicitly returned.

D. The function generates its own this making it useful for separating the function's scope from its enclosing scope.

Question 19 of 20

Refer to the HTML below:

<p> The current status of an Order: <span id="status"> In Progress </span> </p>

Which JavaScript statement changes the text 'In Progress' to 'Completed'?

Choose 1 answer

A. document.getElementById("status").value = 'Completed';

B. document.getElementById("#status").innerHTML = 'Completed';

C. document.getElementById(".status").innerHTML = 'Completed';

D. document.getElementById("status").innerHTML = 'Completed';

Question 20 of 20

A developer wants to leverage a module to print a price in pretty format, and has imported a method as shown below:

import printPrice from '/path/PricePrettyPrint-js';

Based on the code, what must be true about the printPrice function of the PricePrettyPrint module for this import to work?

Test Set 2

Practice Test

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